The OC

When tough, guarded, fiercely intelligent 16-year-old Ryan Atwood (series star BENJAMIN McKENZIE) is arrested for participating in a car theft, idealistic pro-bono public defender Sandy Cohen (series star PETER GALLAGHER) is assigned to the case. But after Ryan's neglectful mother, Dawn (recurring guest star DAPHNE ASHBROOK), banishes Ryan from her house in Chino, Sandy becomes much more involved in Ryan's life than either of them expected. To the chagrin of Sandy's wife, Kirsten (series star KELLY ROWAN)--a wealthy and beautiful former homecoming queen and apparently the perfect spouse, mother and businesswoman--Sandy invites Ryan to stay overnight in the guesthouse of Sandy's lavish Newport Beach home. Kirsten worries how Ryan will influence the couple's teenage son, Seth (series star ADAM BRODY), a soulful dreamer ostracized by his peers.

Meanwhile, Ryan becomes attracted to Marissa Cooper (series star MISCHA BARTON), the heartbreakingly beautiful girl next door who seems to glide through life effortlessly. The indiscretions of Marissa's wealthy father, Jimmy (series star TATE DONOVAN), threaten to break her world apart, however. And Ryan and Seth quickly bond following a clash with some territorial teenagers, including Marissa's jealous boyfriend, Luke Ward (series star CHRIS CARMACK), at a beach party.

Now that Ryan's mother has abandoned Ryan and moved away, Sandy has no choice but to accede to Kirsten's wishes and remand Ryan to Social Services. Facing the prospect of living in a foster home, Ryan prepares to secretly leave on his own. But Seth finds out and suggests a better idea: Together with Marissa, the boys sneak to an unfinished model home, the perfect hiding place for Ryan. Seth's mother, Kirsten, is the head of residential development for The Newport Group, a real-estate company, and is selling the house. Ryan, Seth and Marissa spend hours in the model home's empty swimming pool, bonding, skateboarding and eating.

The next morning, when Seth takes Ryan to a remote beachfront diner, they scuffle with Marissa's boyfriend, Luke, and his friends, with whom they fought at the recent beach party. After discovering that Sandy has reported Ryan to the police as a missing person, Seth and Marissa purchase Ryan a bus ticket to Texas, where he has an acquaintance. Marissa admits that she wishes Ryan wouldn't leave, but he warns her that a relationship between them would never succeed.

Meanwhile, Marissa's materialistic friend, Summer Roberts (recurring guest star RACHEL BILSON), finds out about the plan and, as a result, Luke and his friends break into the home and attack Ryan. During the fight, lit candles are knocked over, setting the house ablaze--along with Ryan's bus ticket and cash. Luke's friends flee, but Luke drags the unconscious Ryan from the burning building before running away.

Kirsten's company does not charge Ryan with arson for the model home burning, but he must remain in juvenile hall until he can be placed in the care of a guardian. Kirsten reluctantly brings Seth to the jail to visit Ryan. During the meeting, a violent inmate almost assaults Kirsten, but Ryan bravely defends her. Fearing for Ryan's life, Kirsten takes temporary custody of him.

After hiring a private detective, Sandy locates Ryan's struggling mother, Dawn (recurring guest star DAPHNE ASHBROOK), and brings her to Orange County for an uncomfortable reunion with Ryan. Dawn has left her abusive boyfriend and wants to work on her drinking problem and be Ryan's true mother again.

Meanwhile, Marissa's father, Jimmy, borrows $100,000 from Kirsten to save his faltering financial business. Since Kirsten and Jimmy dated long ago, Sandy and Jimmy's manipulative and judgmental wife, Julie (recurring guest star MELINDA CLARKE), are concerned when they find out about their spouses' secretive behavior.

At a casino night charity event, Ryan fears that his mother will spoil the evening, while Seth amazingly finds himself acting as a good luck charm for Summer (recurring guest star RACHEL BILSON), the girl he longs for. When Dawn remains poised, Ryan relaxes and enjoys the party, but nervousness soon overcomes her, and she becomes embarrassingly drunk. Later, she remorsefully leaves Ryan again, asking Kirsten to care for him in the way Dawn never could. Ryan is now part of the Cohen family.

Sandy and Kirsten convince child services officials to let them become Ryan's caretakers, and Ryan agrees to stay out of trouble. But with the upcoming cotillion, an old-fashioned formal event at which teenagers make their "debut" in society, that may be hard to do. Reluctantly, Ryan is matched with an iconoclastic East Coast girl, Anna Stern (recurring guest star SAMAIRE ARMSTRONG); to his delight, Seth is paired with the dateless Summer (recurring guest star RACHEL BILSON); Marissa plans to attend with wary Luke; and despite some individual last-minute hedging on Sandy's and Jimmy's parts, all the parents agree to accompany their children to the ceremony.

Meanwhile, agents from the Security and Exchange Commission visit Sandy at work and inform him that Kirsten's check to Jimmy was not treated as an investment but was deposited into Jimmy's personal account. Outraged, Sandy threatens to tell all of Jimmy's deceived clients until Kirsten asks to talk to Jimmy first. Jimmy admits that, due to poor investments and mismanagement--along with the extravagant spending habits of his wife--he is in major financial trouble.

Marissa refuses to go to the cotillion because she had an argument with Luke, and Ryan tries to avoid trouble by staying home as well. When scheming Summer accompanies Luke, rejecting poor Seth, he and Anna discover that they have a lot in common. Later, Marissa persuades Ryan to be her escort after all. At the cotillion, Greg Fisher (recurring guest star CHRISTOPHER COUSINS), one of Jimmy's wealthy clients, becomes suspicious about Jimmy's evasiveness. When Jimmy confesses that he has lost Greg's money, Greg becomes enraged and pummels Jimmy. Chaos ensues as Sandy is injured trying to protect Jimmy, and Ryan finally subdues Greg before anyone else is hurt. The event comes to an unfortunate end as the police arrive.

After befriending a likeable busboy, Donnie (PAUL WASILEWSKI), at a casual seafood restaurant, Ryan takes a job there. Wanting to experience Ryan's social group, Seth accepts Donnie's invitation to a party in Donnie's neighborhood. Ryan fears the Seth doesn't comprehend the type of people he will encounter, so he sacrifices a potential date with Marissa to protect him. During the wild party, the luxury car that Seth borrowed from his mother is destroyed by thieves.

Feeling bad that he prevented Ryan and Marissa from getting together, Seth persuades Marissa to plan another date with Ryan. While the hesitant pair happily shares sandwiches by the pool at the Cohen house, Seth disregards Ryan's advice and allows Donnie and his rough friends to attend a Newport Beach party with him. Ryan must again abandon Marissa to help Seth when Donnie's group becomes uncontrollable, and a fracas between Donnie and Luke results in Luke getting shot in the arm. Unbeknownst to Marissa, who has not spoken to Luke since their argument before the cotillion, Luke and Marissa's friend Holly (recurring guest star ASHLEY HARTMAN) have begun dating.

Kirsten nervously prepares a magnificent birthday party for her widowed father, Caleb Nichol (recurring guest star ALAN DALE), an extremely successful and driven businessman for whom Kirsten works. She is devastated when, rather than being proud of her hard work while he was out of the country, Caleb berates and demotes her for making deals without his approval. The situation worsens when Sandy, whom Caleb has never liked, reveals that Kirsten wants to quit and begin a simpler life away from Newport Beach with Sandy, Seth and Ryan. Caleb's gorgeous 25-year-old girlfriend, Gabrielle (NICHOLE HILTZ), trapped by her businesslike relationship with the much older Caleb, flirts with a conflicted Ryan at his job.

Meanwhile, since being shot in the arm, Luke has become attentive and polite, puzzling Marissa and everyone around him. He apologizes to Marissa and promises to be a better boyfriend if she takes him back, which she does. And furious that she has to give up her glamorous lifestyle because of Jimmy's financial failure, Julie demands a divorce from the distraught Jimmy

Despite being angry with Kirsten, who is hurt by Sandy's premature action, Caleb goes to his well-attended birthday party, along with Gabrielle. Marissa and Luke are there together, and shallow Summer has manipulated Seth into inviting her so she can hunt for rich young bachelors. Jimmy stuns Julie by arriving unexpectedly and desperately asking wealthy Caleb for a job. Caleb refuses--until conniving Julie uses her wiles to make him reconsider hiring her husband. Later, Sandy confronts Caleb and convinces him to reconcile with Kirsten and keep her on staff.

Gabrielle finds depressed Ryan hiding from Marissa in his guesthouse and aggressively seduces him. After Marissa witnesses the shocking scene, she makes a serious decision and goes home with Luke to have sex for the first time. Later, she tells Ryan that it is too late for him to try to date her.

It's the end of summer, and Seth convinces a reluctant Ryan to plan a trip to Tijuana, where hundreds of rowdy teens congregate to indulge in escapist excess before they have to begin school again. In addition to dating Luke again, Marissa is angry with Ryan after witnessing him with an older woman. She also wants to stay home and take care of her overstressed father. But Summer persuades her to come, and the four kids drive south, Ryan and Marissa not speaking to each other and Summer and Seth sparring constantly. During an argument, Seth accidentally drives off the road and damages the car. The friends are forced to stay in a disgusting motel overnight while the car is being repaired.

While Marissa recovers in the hospital from her overdose, everyone remains concerned about her. Julie (recurring guest star MELINDA CLARKE) vents her anger at Ryan, blaming him for all of Marissa's problems and warning him to stay away from her daughter. Meanwhile, Sandy tries to get acclimated to his new job at an affluent corporate law firm. Kirsten is displeased about her husband's rekindled relationship with his attractive former colleague, Rachel Hoffman (recurring guest star BONNIE SOMERVILLE), who is once again his co-worker--especially when Kirsten sees Sandy and Rachel having an intimate after-work cocktail.

Dr. Michelle Kim (recurring guest star ROSALIND CHAO), the dean of Harbor High School, is not happy about the prospect of having a student with a criminal background. She makes Ryan take a placement examination to determine whether or not he will be accepted into the school. Ryan risks his future at Harbor High--and his future in Newport--by leaving in the middle of the test to join Summer (recurring guest star RACHEL BILSON) and Seth in an attempt to save Marissa from being sent away to San Diego. Ryan's risky move could result in both Marissa and him being forced to leave Orange County.

The summer is officially over, and it's the first day of school. Summer (recurring guest star RACHEL BILSON) still ignores Seth in public, but privately she is jealous of Seth's burgeoning relationship with iconoclastic East Coast girl Anna Stern (recurring guest star SAMAIRE ARMSTRONG). And Summer isn't the only person fighting feelings of jealousy. Kirsten still isn't comfortable with Sandy's friendship with his sexy new co-worker, Rachel (recurring guest star BONNIE SOMERVILLE). Rachel makes matters worse when she specifically enlists Sandy to work on a lawsuit that an environmental group has initiated against Kirsten's father and his land development company, despite the obvious conflict of interest. Kirsten is incensed, but conflicted Sandy truly believes in the environmentalists' cause.

Meanwhile in school, Marissa and Ryan become closer, but Luke is still desperate to win her back. When it looks like Luke may succeed, Ryan lets his jealousy overwhelm his reason and starts a fight with Luke. Disappointed in Ryan following the brawl, Marissa must decide whether to forgive his rage or abandon him.

Having seriously dated for one week, Marissa and Ryan are progressing slowly. Summer (recurring guest star RACHEL BILSON) tries to deny her true feelings for Seth as she witnesses Anna (recurring guest star SAMAIRE ARMSTRONG) and Seth getting closer. Meanwhile, the case against Kirsten's father, Caleb (recurring guest star ALAN DALE), continues to cause friction between Sandy and Kirsten. And Julie (recurring guest star MELINDA CLARKE) tries to mend her relationship with Marissa, inviting her, Jimmy and Ryan to attend her charity event--where her new relationship is revealed.

When Seth tries to choose between dating Summer (recurring guest star RACHEL BILSON) or Anna (recurring guest star SAMAIRE ARMSTRONG), he ends up in the middle of a very complicated situation. Meanwhile, Ryan visits his brother, Trey (recurring guest star BRADLEY STRYKER), in prison, accompanied by Marissa. When Julie (recurring guest star MELINDA CLARKE) finds out that Marissa is with Ryan in Chino, she becomes furious. As everyone nervously waits at the Cohen house for Ryan and Marissa to return, tensions mount, making the holiday a Thanksgiving to remember.

After Thanksgiving, Anna (recurring guest star SAMAIRE ARMSTRONG) and Summer (recurring guest star RACHEL BILSON) remain upset with Seth for his behavior on the holiday, and Seth struggles to reconcile with them. Meanwhile, Julie (recurring guest star MELINDA CLARKE) has relationship problems of her own. Jimmy and Sandy team up to tackle Jimmy's legal issues. A secret indiscretion by Kirsten is exposed. Ryan and Luke become partners on a history project, and an astonishing revelation creates an unexpected alliance between them.

Seth excitedly introduces a skeptical Ryan to Chrismukkah, a Cohen family tradition that resulted from Kirsten being Christian and Sandy being Jewish. As everyone prepares for a huge holiday party organized by Julie (recurring guest star MELINDA CLARKE), Seth continues attempting to juggle Anna (recurring guest star SAMAIRE ARMSTRONG) and Summer (recurring guest star RACHEL BILSON), both of whom want to date him exclusively. Meanwhile, on opposing sides of a lawsuit, Sandy and Kirsten dread working through the holiday season, but Kirsten learns something about her father that could change everything. And Ryan and Marissa's shopping trip leads to trouble--and the beginning of even bigger problems for Marissa.

Kirsten's rebellious 25-year-old sister, Hailey Nichol (recurring guest star AMANDA RIGHETTI), comes to town on New Year's Eve, causing turmoil in the Cohen household. Ryan and Marissa plan a quiet evening of popcorn and movies at home, but Marissa later decides to attend a party hosted by a young man, Oliver Trask (recurring guest star TAYLOR HANDLEY), who goes to the same therapist as she does. Meanwhile, Hailey persuades Sandy and Kirsten to go out so she can have a raging party in their house for a few friends. As the clock ticks closer to midnight, Ryan hopes that he can make it to Marissa in time for their first New Year's kiss together. As of this episode, MELINDA CLARKE as Julie Cooper and RACHEL BILSON as Summer Roberts are series stars.

Kirsten's unemployed sister, Hailey (recurring guest star AMANDA RIGHETTI), moves in with the Cohens and disrupts the entire family when she behaves as the houseguest from hell. Hailey depletes the refrigerator, controls the television, disrespects Kirsten and shows no signs of leaving anytime soon. Desiring some time alone with his wife, Sandy urges Kirsten to resolve the problem with her sister. When Kirsten can't confront Hailey, Sandy angrily tells Hailey that everyone is tired of tolerating her rude behavior. Meanwhile, Seth and Anna (recurring guest star SAMAIRE ARMSTRONG) struggle with telling Summer the truth that they are now a couple. Ryan feels jealous about Marissa's new friend, Oliver (recurring guest star TAYLOR HANDLEY), a neglected, drug-abusing teen she met in therapy who always seems to show up when Ryan wants some privacy with Marissa. Later, Ryan helps Oliver by asking Sandy to intervene when Oliver is arrested for trying to buy drugs from an undercover cop.

Ryan, Seth, Marissa, Anna (recurring guest star SAMAIRE ARMSTRONG), Luke and Summer head to Palm Springs for a parent-free weekend at the home of Marissa's new, troubled friend Oliver (recurring guest star TAYLOR HANDLEY). Hoping to spend some time alone with Marissa, Ryan, who is neither interested in golf nor spas, reluctantly agrees to make the road trip with Luke. Oliver quickly irritates Ryan by flirting with Marissa and deliberately keeping the couple apart. And Summer uses every method she can to annoy Seth and Anna. The weekend goes from bad to worse when Oliver angrily leaves the house only to later phone Marissa with news that he's taken a handful of drugs to commit suicide. Marissa and Ryan race to a hotel where Oliver seems to be shaken but in no apparent danger of overdosing. Ryan is unconvinced that Oliver even attempted to take his life, and much to Ryan's dismay, Marissa insists on staying the night alone with Oliver.

Meanwhile, Kirsten talks to Caleb (recurring guest star ALAN DALE) about Hailey's (recurring guest star AMANDA RIGHETTI) ongoing financial problems and her lack of independence. Hailey is outraged that Kirsten has interfered with her plans of getting money from their father and decides to move out of Kirsten and Sandy's home. In Orange County, Jimmy has no job prospects, but after dinner at The Lighthouse, Jimmy and Sandy reach a tentative agreement to go into business together and buy the restaurant.

Sandy and Jimmy begin a new business partnership when they buy The Lighthouse, a beloved Newport restaurant. Meanwhile, Kirsten and Julie become workmates when Julie is hired as Newport Group's new model-home designer. Also, Seth's jealousy of Summer's new boyfriend causes Seth to doubt his relationship with Anna (recurring guest star SAMAIRE ARMSTRONG). And Ryan loses control while trying to prove that Marissa's troubled friend Oliver (recurring guest star TAYLOR HANDLEY) is a fraud, leaving Seth and the Cohens concerned and afraid for Ryan.

Caleb (recurring guest star ALAN DALE) once again puts Kirsten in a difficult situation when he forces her to terminate Julie. After yet another crisis with Ryan, Sandy and Kirsten question their decision to bring him into their home. Meanwhile, Ryan and Luke become allies in their quest to protect Marissa from Oliver (recurring guest star TAYLOR HANDLEY). When Marissa discovers the truth about Oliver, a tense showdown ensues--and Sandy and Ryan must come to the rescue.

Marissa tries to mend her relationship with Ryan, but he can't forgive her for the situation with Oliver. Things become even more complicated when Theresa (recurring guest star NAVI RAWAT), Ryan's ex-girlfriend from Chino, arrives to waitress at Kirsten's Valentine's Day dance. Meanwhile, Seth and Summer decide to take their friendship to a new level, and Jimmy finds out he has a secret admirer.

Marissa and Ryan try to start over as friends, but it's not as easy as they had hoped. As Theresa (recurring guest star NAVI RAWAT), Ryan's ex-girlfriend from Chino, begins spending more time in Newport, Ryan discovers that she hasn't been honest about why she's there. Seth believes his relationship with Summer is great, but when she refuses to acknowledge him at school, he feels he has to teach her a lesson. Meanwhile, Sandy finds himself embroiled in another mess created by Caleb (recurring guest star ALAN DALE). And Jimmy begins to suspect something is going on between Julie and Luke.

When Theresa (recurring guest star NAVI RAWAT) decides to stay in Newport, Ryan is glad, but he feels obligated to help her find a job and a place to live. Julie and Luke's affair continues to flourish, but their secret is threatened when Jimmy witnesses an intimate moment between them. Meanwhile, Anna (recurring guest star SAMAIRE ARMSTRONG) announces that she is moving back to Pittsburgh. Convinced that her leaving is his fault, Seth races to the airport to stop her.

When actor Grady Bridges (COLIN HANKS - "Orange County," "Roswell") invites Summer and Marissa to his birthday party, the girls take Ryan and Seth to Los Angeles to join in the festivities. At the party, Summer is thrilled to spend time with Grady, but Seth is not as happy. The situation is reversed when Seth meets sexy Kate (PARIS HILTON - "The Simple Life"), and it's Summer's turn to be jealous. Afterwards, the gang heads back to Orange County, where Ryan has a hard time keeping Luke and Julie's affair a secret from Marissa.

The Cohen family prepares for a visit from Sandy's mother, Sophie (LINDA LAVIN - "Alice"), for Passover dinner. Fearing that his grandmother will not approve of Summer, Seth tries to keep the two from encountering each other--but Summer sets out to prove him wrong. Meanwhile, Ryan desperately searches for Marissa, who disappeared when she found out about Luke and Julie's affair.

Marissa isn't ready to speak to Luke or her mother, Julie, following her discovery that the two have been having an affair. Luke is desperate to explain himself. When he gets into a near-fatal accident, however, both Marissa and Ryan decide to listen to what he has to say. Meanwhile, it's opening night for new restaurant The Lighthouse. Just prior to opening, Jimmy and Sandy are shocked to find out that their liquor license has been denied, and Sandy is faced with the choice of getting the license or keeping Jimmy as his partner. Also, Caleb (recurring guest star ALAN DALE) uses the occasion to surprise everyone by proposing marriage to Julie.

Every bride-to-be must have a wedding shower, and Julie is going to have one to remember, thanks to Marissa. Meanwhile, Theresa (recurring guest star NAVI RAWAT) returns to Newport Beach. When Ryan finds out why she came back, he is shocked. And Seth gets the chance to meet Summer's father, but it doesn't go as well as anyone would have liked.

These are Caleb's (recurring guest star ALAN DALE) last days as a bachelor, and he's spending them in Las Vegas. Seth and Ryan join him in "Sin City" for the celebration while a reluctant Kristen plans a bachelorette party for Julie back home in Newport Beach. Meanwhile, Marissa and Theresa (recurring guest star NAVI RAWAT) are learning more about each other, but what Marissa finds out about Teresa could have big consequences.

It's Julie Cooper's wedding day, and it will be a day to remember for more people than just the blushing bride. Recording artist JEM performs Paul McCartney's "Maybe I'm Amazed" during the ceremony. But the wedding is only the beginning of a series of events that will change many lives in Orange County forever.

The lives of a group of friends and families have been forever changed by the arrival of an outsider to their affluent oceanside community of Newport Beach in Orange County, California. When Ryan Atwood (series star BENJAMIN McKENZIE) was taken in from the streets of Chino by then public defender Sandy Cohen (series star PETER GALLAGHER), the Cohens had no idea how Ryan's arrival would affect them and those around them. Initially resistant, Kirsten (series star KELLY ROWAN) opened her heart to accept the outsider just as she had accepted Sandy, another outsider, into her old-money Newport Beach family. In Ryan, their "adorkable" son, Seth (series star ADAM BRODY), found a friend and brother with whom he could share his quirky way of looking at the world. Seth also struggles with the trials and tribulations of winning the heart of Summer Roberts (series star RACHEL BILSON), his lifelong crush.

Summer is over, and school is in session. Seth and Ryan hope to win back the attention they once had from Summer and Marissa. With opportunity beckoning, Hailey (recurring guest star AMANDA RIGHETTI) tells Jimmy about her plans to move in order to pursue her unfulfilled fashion ambitions. Hoping to keep her near, Jimmy does something unimaginable. Meanwhile, Sandy explains to Julie that the district attorney is keeping a close watch on Caleb, and without representation, he might be in for a confrontation. Julie threatens Sandy to do something about Caleb's messy situation or face her wrath.

At the Bait Shop, the new music club on the pier, Seth gets some help from his attractive and tough-talking manager, Alex (recurring guest star OLIVIA WILDE - "The Girl Next Door," "Skin"), to prove that his friends don't know him as well as they think. Meanwhile, Summer gives some thought to how she really feels about Seth after she learns more information about her new boyfriend, Zach (recurring guest star MICHAEL CASSIDY). Marissa is happy to share an evening with Ryan. But at school, Ryan is embarrassed and frustrated after a confrontation with new classmate Lindsay (recurring guest star SHANNON LUCIO). Caleb's legal problems threaten to leave both Sandy and Kirsten unemployed as Julie makes sure she stays in power--even if Caleb is ruined.

Seth, who is now without a girlfriend, and Sandy, who has just been fired from the law firm, embark on new eras in their lives and vow to take the whole family with them. Ryan and Seth go on an awkward double date to see THE KILLERS (themselves) perform at the Bait Shop, with unexpected results. Meanwhile, Julie finds herself overwhelmed by her new role at the Newport Group and, as usual, is forced to turn to Kirsten for help.

The winter season finally comes to Newport, and Seth, Ryan, Summer and Marissa attend the annual SnO.C. Winter Ball. Julie and Jimmy spend some quality time together as the chairs of the host committee, and Sandy gets closer to the truth Caleb has been hiding. Meanwhile, Julie discovers Marissa's secret when Marissa leaves school at lunch and goes home to meet D.J. (recurring guest star NICHOLAS GONZALEZ).

The whole gang is invited to Chrismukkah at the Cohens' house, but Seth's favorite holiday is nearly ruined as secrets are revealed that will change the Cohen family forever. Summer, Marissa and Ryan make a plan to save Chrismukkah.

Ryan tries to come to terms with his feelings for Lindsay. Now that she may become a member of the Cohen family, their attraction is rather awkward. Although Sandy knows they're dating, Ryan and Lindsay keep the relationship hidden from Kirsten. Meanwhile, Caleb learns that the criminal charges against him have been dismissed. And in an effort to impress Alex, Seth tries to cultivate a "bad boy" image by dressing like Ryan, getting drunk and stealing Caleb's prized sports car. Marissa sees Jimmy and Julie kissing aboard his boat and is hurt and angry with her father. Jimmy finally realizes that after all the trouble and heartache he's caused, the best thing he can do for himself and his daughter is to leave Newport and move to Maui...but not before a big going-away party at the Cohens' house. Devastated by the situation with her parents, Marissa comes to the party intoxicated and yells at both of them.

Lindsay (recurring guest star SHANNON LUCIO) and Ryan grapple with their new relationship: Is Lindsay Ryan's step-aunt or his girlfriend? Meanwhile, Summer meets Zach's (recurring guest star MICHAEL CASSIDY) family, and it doesn't go so well. In the end it's an anniversary to remember as Sandy surprises Kirsten with a serenade at the Bait Shop. But Marissa ends up alone as D.J. (recurring guest star NICHOLAS GONZALEZ) leaves Newport Beach.

It's girls against boys when Marissa and Summer decide to plan a girls' night out and include Lindsay (recurring guest star SHANNON LUCIO) in the festivities. Left to their own devices Ryan, Seth and Zach (recurring guest star MICHAEL CASSIDY), have a bonding session over video games and pizza but find it hard to stay away from their female counterparts. Julie and Kirsten collaborate on an idea to help the image of the Newport Group while Sandy and Caleb try to convince them there may be a better way.

Seth and Zach (recurring guest star MICHAEL CASSIDY) decide to create a comic book based on their lives in Newport Beach. While browsing through the sketches, Summer wonders why she's been left out. Sandy decides to help an old friend, Professor Max Bloom (recurring guest star BARRY NEWMAN - "40 Days and 40 Nights," "Petrocelli"), find his daughter, Rebecca (recurring guest star KIM DELANEY - "CSI: Miami," "NYPD Blue"), but the search leads to even more questions. While Julie is away, Marissa's contempt for Caleb grows as she looks for new ways to rebel. Meanwhile, Ryan tries to help Lindsay (recurring guest star SHANNON LUCIO) satisfy her curiosity about Caleb.

Summer decides to take an active role in creating the comic book, but Seth doesn't know if he can handle spending that much time alone with her. Sandy and Rebecca (recurring guest star KIM DELANEY) reminisce about days gone by as Kirsten tries to convince Caleb that he could have a familial relationship with Lindsay (recurring guest star SHANNON LUCIO). Meanwhile, Caleb decides what kind of future he wants to have with his daughters. And Alex (recurring guest star OLIVIA WILDE) asks Marissa where their friendship is going. Chicago singer/songwriter RACHEL YAMAGATA performs.

Sandy tries to make amends with Kirsten for keeping Rebecca's (recurring guest star KIM DELANEY) return a secret by showering his wife with Valentine's Day gifts. Zach (recurring guest star MICHAEL CASSIDY), Summer and Seth drive to San Diego to pitch their comic book idea, and Seth is determined to use the trip to get Summer back. Julie returns from her European vacation and has decided to reconnect with Marissa. Meanwhile, Ryan wants to spend Valentine's Day with Lindsay (recurring guest star SHANNON LUCIO), but her loyalty to Caleb gets in the way.

While Rebecca (recurring guest star KIM DELANEY) pays her last respects to her father, Kirsten grows impatient with Sandy's long absences from home and decides to visit Rebecca. Alex (recurring guest star OLIVIA WILDE) invites Marissa to hang out with her friends. Meanwhile, Caleb decides to remove all doubt that Lindsay (recurring guest star SHANNON LUCIO) is his daughter.

It's raining in Newport. Marissa tells Julie that she and Alex (recurring guest star OLIVIA WILDE) are dating and decides she has to get out of Caleb's house. Summer is faced with a big decision as she prepares to go to Italy with Zach (recurring guest star MICHAEL CASSIDY). Ryan convinces Lindsay (recurring guest star SHANNON LUCIO) to take the paternity test, and everyone anxiously awaits the results. Meanwhile, Sandy is stranded in a motel room with nothing but a few snacks, champagne and Rebecca (recurring guest star KIM DELANEY).

Although she is trying hard to make her new living situation work, Marissa feels she needs a break and agrees to join Summer, Seth and Ryan at the mall. Julie and Kirsten await the arrival of Carter (recurring guest star BILLY CAMPBELL - "Enough," "The Rocketeer"), the new editor of Newport Living, but Julie is distracted when she's visited by Lance (recurring guest star JOHNNY MESSNER - "Spartan," "The Whole Ten Yards"), an opportunistic man from her past. Meanwhile, Sandy and Caleb finally bond over all of their recent experiences.

Seth is determined to bring back the spirit and fun times of last year and won't stop until his plan is successful. Alex's (recurring guest star OLIVIA WILDE) jealousy is fueled when Marissa enlists an unlikely partner to help her with the school bonfire. Meanwhile, Kirsten wants Carter (recurring guest star BILLY CAMPBELL) to continue with the magazine despite his reservations, and Sandy helps Julie keep her blackmailer at bay.

When someone from Ryan's past comes for a visit, he worries that nothing good can come of it; while the Cohen family welcomes the Chino visitor with open arms. As Marissa and Ryan continue to explore their newfound friendship, Seth and Summer face some unforeseen news. Meanwhile, Julie admits her mistake to Kirsten and looks to Caleb for help.

When Sandy becomes the honorary chairman of the Newport Beach charity yard sale, he solicits help from Trey (recurring guest star LOGAN MARSHALL-GREEN), who has his first confrontation with the Newpsies. While Sandy auctions off Newport's finest, Kirsten and Carter (recurring guest star BILLY CAMPBELL) share a table. When one of the auction's most expensive pieces goes missing, Ryan and Seth could also use some help. Meanwhile, Trey looks for a more permanent place to live as the Cohens welcome yet another houseguest.

Eager to help Trey (recurring guest star LOGAN MARSHALL-GREEN) and Ryan repair their relationship, Marissa hosts a birthday party for Trey at Caleb's mansion that quickly gets out of control. After surfing with Carter (recurring guest star BILLY CAMPBELL), Sandy suggests introducing him to a woman friend, to Kirsten's chagrin. When Summer finds out what Seth's potential graphic novel publisher, Reed (recurring guest star MARGUERITE MOREAU), is really like, Seth is in big trouble. And after leaving town in disgrace, Julie returns and surprisingly ends up reminiscing with an old acquaintance.

After the wild party at Caleb's mansion, Sandy, Seth and Ryan devise a plan to save another Atwood from going to jail. Kirsten and Carter (recurring guest star BILLY CAMPBELL), fulfilling more than their editorial duties, take a trip to the wine country. Meanwhile, Caleb returns from Europe and rebuffs Julie's romantic advances. The band DEATH CAB FOR CUTIE performs.

Sandy, Seth and Ryan travel to Florida to visit Seth's Nana, Sophie (recurring guest star LINDA LAVIN - "Alice "), who is living in Miami Beach. While playing shuffleboard at the coastal retirement community, Seth and Ryan meet Mary-Sue (JAIME KING - "Sin City"), who helps Seth get center stage on the Music Video Nation spring break television special, hosted by Swerve (BRET HARRISON), along with Pixie (KRISTA KALMUS), who is a star of "Sherman Oaks: The Real Valley." Meanwhile, on the West Coast, Carter (recurring guest star BILLY CAMPBELL) packs his bags and leaves Kirsten alone at the offices of Newport Living, and Trey (recurring guest star LOGAN MARSHALL-GREEN) misinterprets Marissa's friendship. Also, rapper T.I. (himself) performs his hit single "Bring Em Out."

Since Carter's departure, Kirsten has been drinking more than just tomato juice for breakfast, and when Sandy questions her, he's left to sleep alone in the bedroom. Marissa's nervousness around Ryan leads him to wonder if something has happened between her and Trey (recurring guest star LOGAN MARSHALL-GREEN). Summer, tired of Seth and Zach (recurring guest star MICHAEL CASSIDY) behaving foolishly, confronts Reed (recurring guest star MARGUERITE MOREAU) about the graphic novel and finds herself center stage at the Atomic County launch party. Meanwhile, Caleb shows Julie that a picture is worth a thousand words.

Sandy and Caleb confront Kirsten about her behavior. Ryan heads home to Chino, as he looks for the truth about Trey (recurring guest star LOGAN MARSHALL-GREEN) and Marissa. Meanwhile, Summer refuses to let her three-way relationship with Zach (recurring guest star MICHAEL CASSIDY) and Seth stop her from attending the prom. And, Julie and Caleb toast to their final evening together as husband and wife.

In the season finale, Sandy must make a life-changing decision to save his marriage to Kirsten. Seth, Summer, Marissa and Ryan are caught in the crossfire at The Bait Shop; and Jimmy Cooper (former series star TATE DONOVAN), worried about Marissa and his family, rushes home to Newport Beach.

The lives of a group of friends and families have forever been changed by the arrival of an outsider to their affluent ocean-side community of Newport Beach in Orange County, California. When Ryan Atwood (series star BEN McKENZIE) was taken in from the streets of Chino by then public defender Sandy Cohen (series star PETER GALLAGHER), the Cohens had no idea how Ryan's arrival would change their lives and the lives of those around them. Initially resistant, Kirsten Cohen (series star KELLY ROWAN) opened her heart to accept the outsider just as she had accepted Sandy, another outsider, into her powerful old-money Newport Beach family. Their "adorkable" son, Seth (series star ADAM BRODY), found a friend and brother in Ryan to share his quirky way of looking at the world--and the trials and tribulations of winning the heart of Summer Roberts (series star RACHEL BILSON), Seth's lifelong crush.

Chaos reigns in the Cohen kitchen as Sandy, Ryan and Seth continue to cope with Kirsten's rehab. When Sandy encourages Kirsten to come home to her family, Kirsten's attachment to Charlotte (recurring guest star JERI RYAN) raises concern in Sandy. Meanwhile, at The Harbor School, Dean Hess (recurring guest star ERIC MABIUS - "Eyes"), the new Dean of Discipline, arrives and makes a decision that changes Marissa's life forever. Summer trumps her cardigan-wearing, goody two-shoes nemesis Taylor Townsend (recurring guest star AUTUMN REESER) when planning the annual Kick-Off Carnival. And Jimmy (recurring guest star TATE DONOVAN) offers Julie a surprising proposal.

Although they are finally happy with each other, Marissa and Ryan are forced to stay apart by their parents, Julie and Sandy. Dean Hess (recurring guest star ERIC MABIUS) pressures Seth and Summer into showing Harbor school spirit, which leads them to devise a covert plan to bring Marissa and Ryan together. When the scheme works, Marissa and Ryan have a night to remember, and Seth and Summer get caught by Taylor (recurring guest star AUTUMN REESER). Meanwhile, Caleb's will is read, leaving Julie stunned and Jimmy in dire straits.

Marissa adjusts to life in her new surroundings and makes some new friends at Newport Union, while Ryan wonders how their separation will affect their relationship. Seth's feud with Dean Hess (recurring guest star ERIC MABIUS) lands Summer in trouble, but some startling new information about Taylor (recurring guest star AUTUMN REESER) may turn the tables once more. Kirsten's friend Charlotte (recurring guest star JERI RYAN) lands in Newport with some big ideas, while Sandy mulls over the future of the Newport Group. Meanwhile, Julie may no longer be a Newport Beach socialite.

Ryan makes a life-changing decision that Sandy surprisingly supports, and Marissa turns to her new public school friends for help with Ryan. The Harbor School's Dean of Discipline, Dean Hess (recurring guest star ERIC MABIUS), continues his crusade to ruin Ryan's future, and Summer and Seth go on their own crusade to reveal Dean Hess's secret. Meanwhile, Charlotte (recurring guest star JERI RYAN) makes Julie an offer she cannot refuse.

Taylor ruins Seth's night by keeping Summer away. Marissa's new friendships at public school worry Summer. Sandy forms a new partnership. Charlotte manipulates Julie and Kirsten.

When the gang heads to The Bait Shop to see the British rock band THE SUBWAYS (themselves), Taylor's behavior causes a major rift between Seth and Summer. Determined to end the potentially explosive conflict between Ryan and Kevin Volchok (recurring guest star CAM GIGANDET), Marissa watches out for Ryan. Meanwhile, Matt (recurring guest star JEFF HEPHNER), Sandy's Newport Group partner, goes above and beyond the call of duty. Julie reigns supreme as the only bitch in Orange County, and for once, Ryan must control his anger.

As seniors at Harbor School and Newport Union prepare their college applications, Ryan, Seth, Summer and Marissa decide what to do about their futures. Will they go to college? Unable to make a decision, Marissa attends Johnny's (recurring guest star RYAN DONOWHO) surf competition instead of completing her college application. Meanwhile, Julie is forced to return to her roots, and Kirsten, eager to get back to work, asks a friend for help. Sandy invites an old friend from UC Berkeley to dinner with Seth and Ryan. Alternative rockers THE SUBWAYS perform. Former series star TATE DONOVAN makes his directorial debut.

Ryan takes an internship working for Sandy and Matt (recurring guest star JEFF HEPHNER) at the Newport Group, but he ends up working harder to save Matt's reputation. Determined to get accepted to Brown University, Summer and Seth do whatever it takes to stand out at Harbor School. Johnny (recurring guest star RYAN DONOWHO) finally tells Marissa how he really feels about her. After a stressful weekend, Ryan and Marissa cross paths and end up telling each other the truth about their time apart.

After the teens spend hours picking out the perfect Christmas trees, they devise a special plan to help a friend in need. Meanwhile, missing her mom, Summer feels even more somber during this holiday, and Johnny's (recurring guest star RYAN DONOWHO) sudden misfortune forces him to take matters into his own hands. Kirsten tries to put the past behind her and make amends with Julie. Reminiscing Seth vows to put a little "mukkah" into Ryan's "chris," and Ryan gets "Bar Mitz-vahkkahed" on the third annual Chrismukkah episode.

Summer, Seth and Ryan launch a campaign to get Marissa back into The Harbor School, and Johnny (recurring guest star RYAN DONOWHO) struggles between a friend's happiness and his own feelings. Meanwhile, Sandy must make an ethical decision that could change Marissa's fate, and Summer's father, Dr. Neil Roberts (recurring guest star MICHAEL NOURI), and Julie are apprehensive about admitting to the lies they have told their daughters.

Fourteen-year-old Kaitlin Cooper (recurring guest star WILLA HOLLAND) returns to Orange County during her winter break from an exclusive Montecito boarding school--bringing a lot of attitude and a few secrets. Much more in the mold of her mother, Julie, than her sister, Marissa, Kaitlin turns heads as she tries to get closer to her family in the only way she knows how.

While Marissa does all she can to get to know her sister again, Kaitlin (recurring guest star WILLA HOLLAND) just stirs up trouble for the gang as she prepares to celebrate her birthday. Meanwhile, Sandy encourages Seth about college, but Seth finds a better alternative. Sandy and Matt (recurring guest star JEFF HEPHNER) work together to secure a contract for the new hospital. And Julie continues her quest to put her family back together.

Summer discovers the truth about Seth. Sandy and Matt (recurring guest star JEFF HEPHNER) encounter an obstacle to their hospital project. Kirsten and Julie take their matchmaking business a little too far, causing Julie to go into hiding. Marissa finally tells Johnny (recurring guest star RYAN DONOWHO) how she truly feels. And Kaitlin (recurring guest star WILLA HOLLAND) wonders which Cooper Johnny really likes.

Tragic news forces the friends to sort out their problems and face the reality of the situation. After Johnny's cousin, Sadie Campbell (recurring guest star NIKKI REED), arrives in Newport, Ryan helps her move and get rid of Volchok (recurring guest star CAM GIGANDET), causing Ryan to question his and Marissa's relationship. Meanwhile, Kaitlin's (recurring guest star WILLA HOLLAND) winter break is over. Just as she gets close to her family, she once again has to say goodbye. And in the wake of Newport's latest events, Kirsten and Julie press on with their Valentine's Day party.

Sadie (recurring guest star NIKKI REED) and Ryan go on a road trip to find one of Johnny's relatives. Although Ryan returns to his old "Chino" ways, the trip brings him and Sadie closer. Could this mean the end of Ryan and Marissa's relationship? Meanwhile, Marissa is implicated in Johnny's death, and Seth and Summer discover Julie and Dr. Roberts' (recurring guest star MICHAEL NOURI) secret. Musician TOM VEK performs.

Ryan struggles with the decision of whether or not to invite Marissa to his birthday party, and Sandy wants to include one of Ryan's relatives in the celebration. Meanwhile, Julie and Dr. Roberts (recurring guest star MICHAEL NOURI) come clean with Summer and Marissa. Also, Ryan and Sadie (recurring guest star NIKKI REED), along with fellow new couple Marissa and Volchok (recurring guest star CAM GIGANDET), grow closer.

When an old nemesis returns to Newport, Ryan gets caught up in helping her, causing a rift between him and Sadie (recurring guest star NIKKI REED). Seth and Summer are faced with a new problem that Taylor (recurring guest star AUTUMN REESER) tries to solve. Meanwhile, Marissa finds herself all alone in Newport with no one to turn to, and Sandy grapples with business pressure.

Julie and Dr. Roberts (recurring guest star MICHAEL NOURI) announce their engagement, and the Cooper ladies move in with Summer and her dad. Meanwhile, Marissa drifts away from Summer and the group when she seeks solace in the company of bad boy Volchok (recurring guest star CAM GIGANDET) and his crew. Ryan tries to move on with Sadie (recurring guest star NIKKI REED), but Seth's concern for Marissa gets in the way. At the Newport Group, Sandy's woes with Matt (recurring guest star JEFF HEPHNER) continue. And Kirsten surprises Seth with a night out.

The kids receive their college acceptance and rejection letters, forcing them to make some life-altering decisions. Ryan and Sadie (recurring guest star NIKKI REED) try to decide what do after high school, and their decision concerns Sandy and Kirsten. Taylor (recurring guest star AUTUMN REESER) throws a college sweatshirt party at Harbor High School, and Marissa and Summer patch up their friendship. Meanwhile, the drama surrounding Sandy's job intensifies and starts to affect the Cohen household.

Ryan leaves Newport to visit his mom, but before they meet, he has a steamy encounter with her co-worker. Meanwhile, Seth is keeping secrets, and Taylor (recurring guest star AUTUMN REESER) and Summer devise a foolproof plan to figure out what's going on with him. When their plan backfires, Summer is devastated. Julie Cooper visits a surprised Volchok (recurring guest star CAM GIGANDET) and gives him some stern advice. Later, Marissa confronts Volchok's friends and saves a girl from an intense situation at a raging party. Meanwhile, Sandy puts an end to the trouble with Matt (recurring guest star JEFF HEPHNER) but leaves Kirsten at home alone.

With graduation just weeks away, Ryan, Seth, Summer and Marissa leave Newport to attend their respective pre-freshman orientations at Berkeley and Brown. While dropping the boys off at the airport, Kirsten is surprised to see Theresa (recurring guest star NAVI RAWAT) and her familiar-looking baby boy. At Brown, Seth runs into Anna (recurring guest star SAMAIRE ARMSTRONG), and they instantly connect. Meanwhile, Kirsten and Sandy attend a hospital benefit where Kirsten vents her frustration and falls back into an old habit.

Harbor School's senior prom brings out the best and the worst in everyone. Taylor (recurring guest star AUTUMN REESER) has a great time, while Summer doesn't enjoy herself with her surprising prom date. Seth and Anna (recurring guest star SAMAIRE ARMSTRONG) come up with a plan to win Summer back for Seth. Meanwhile, Marissa convinces Volchok (recurring guest star CAM GIGANDET) to go to the prom with her, and Ryan brings an unexpected old flame. When one of the girls is elected prom queen, it truly becomes a night to remember. Later, when Taylor's prom funds are discovered to be missing, Ryan returns to his old ways, and prom night turns brutal. LISA TUCKER ("American Idol") guest stars as herself.

Dealing with the repercussions from prom night, Ryan must make a deal with Volchok (recurring guest star CAM GIGANDET). Meanwhile, although Sandy is named Man of the Year by a magazine, the district attorney continues to investigate his unique involvement with the new hospital. After she receives a call for help from Kaitlin (recurring guest star WILLA HOLLAND), Marissa visits her little sister at boarding school. Ryan's bloodied hands force Theresa (recurring guest star NAVI RAWAT) to make a difficult decision. And Seth's actions ignite even more trouble in Newport.

The end of senior year is finally here, bringing the excitement of graduation and the anticipation of new lives in college and beyond. But for Seth, Ryan, Marissa and Summer, it's also a time to look back on the amazing journey that has brought the four of them this far. Seth must confront his recent misdeeds or deal with the wrath of Sandy--and the police. Ryan's proud mom arrives with a surprise for him. Marissa receives an astounding proposal that may radically change her plans. And Summer, facing the prospect of going away without Seth, can't stop crying and hugging her best friends as they say their farewells. Kaitlin (recurring guest star WILLA HOLLAND) returns and moves into Julie's home, vowing to become the next Cooper to rule Harbor High. And to Taylor's (recurring guest star AUTUMN REESER) joy, the "core four" turns into the "fab five." However, although the kids may be ready to move on to bright futures, unresolved issues from their past could ruin everything.

In the fourth season premiere, everyone struggles to adjust to life without Marissa. Dealing with her death in the only way he knows how, Ryan has moved out of the Cohen house. When Ryan misses a special dinner, Seth finds him in the wrong part of town and calls Summer for help. Meanwhile, Julie Cooper (series star MELINDA CLARKE) will do anything--even yard work--to avoid dealing with the loss of Marissa. Kaitlin earns a new pair of boots from Dr. Roberts in true Cooper fashion. And Taylor Townsend (series star AUTUMN REESER) hides out in the diner and tries to convince her friends that she is in Paris.

Ryan travels to Mexico--with a stubborn Seth in tow--to put an end to his turmoil in the only way he knows how, but he comes up empty in quest for revenge. Meanwhile, Seth meets some new friends in Mexico, including a Marine (STEVE-O - "Jackass"), who help him find what he is looking for. Harbor School's new female dean of discipline, Dean Torres (TIA CARRERE - "True Lies," "Relic Hunter"), forces Kaitlin and Julie to work together on Harbor's clothing drive. And the Cohens ostracize Julie when they discover that she was part of Ryan and Seth's activities. Also, after Taylor visits Summer unannounced, the truth about Paris comes out, and Summer continues separating herself from everything related to OrangeCounty.

It's Thanksgiving morning at the Cohen house, and the family is still dealing with what happened in Mexico. Sandy makes a deal to help Volchok (recurring guest star CAM GIGANDET) but lets Ryan intervene and finally settle the score. Meanwhile, as Summer packs for a trip home to visit her family and Seth for the holiday, she wonders if she can deal with Newport anymore. And unable to cope with either Kaitlin or Dr. Roberts (recurring guest star MICHAEL NOURI), Julie spends most of Thanksgiving alone.

When Summer tries to become the gossip-loving girl she once was, she realizes that Brown may have changed her forever. Fortunately, Seth continues to be supportive of the new Summer through all of her endeavors. Similarly, Ryan empathizes with Taylor and surprisingly helps her out of a bind. Meanwhile, Julie and Kaitlin attempt to stay out of trouble, but neither can resist temptation.

Summer and Che (recurring guest star CHRIS PRATT) take their activism to a new level, resulting in more freedom than they expected. Meanwhile, after Julie flirts with a hot tennis instructor whom Kaitlin likes, the younger Cooper gets her revenge at a charity party. But later, Kaitlin helps save Julie and Kirsten's dating service. Attracted to Ryan, Taylor tries to cure his insomnia with her own therapeutic plan. When all of her schemes fail, she turns to Kaitlin for advice on how to get her way with Ryan.

When Seth visits Summer at Brown, he finds an empty dorm room. Meanwhile, Sandy and Kirsten take advantage of an opportunity to bond with Ryan, who is in a Taylor-induced haze. Kaitlin meets the mean girl of Harbor School and tries to best her by throwing a huge party at the Roberts house. Julie learns that Newmatch is more than just a dating service. And the truth about Che (recurring guest star CHRIS PRATT) comes out.

It's time for another Chrismukkah in Orange County. After Ryan and Taylor have an accident while hanging holiday lights, they realize that everything is not as it seems, and they must do whatever it takes to make things right again. Former series star TATE DONOVAN guest stars as Jimmy Cooper.

As the new year approaches, Ryan plans a special surprise road trip for Taylor and himself. But when Summer confronts Seth about not making any plans, Ryan's romantic getaway for two is spoiled. Later, Summer's future rests in the hands of a shady character that the gang meets on the way to Las Vegas. Meanwhile, Julie's accounting practices come under some unwanted scrutiny.

Newly engaged Seth and Summer both panic about the prospect of being married, but neither will break it off, despite the advice of their friends. Instead, they begin a complicated game of one-upmanship that almost leads them to Las Vegas for a wedding. Meanwhile, when Ryan's estranged biological father, Frank (recurring guest star KEVIN SORBO), who has been in prison for years, tries to reconcile with Ryan, Sandy remains dubious--and his instincts about Frank may just be correct. Also, rebellious Kaitlin's teacher orders her to be tutored by an insightful classmate, Will Tutt (recurring guest star musician CHRIS BROWN).

Taylor's ex-husband, Henri-Michel (HENRI LUBATTI), gets a little too close to home while promoting his erotic memoirs. After Henri-Michel tells Ryan about Taylor's exciting life in France, Ryan questions his own relationship with Taylor. Meanwhile, Seth visits Dr. Roberts (recurring guest star MICHAEL NOURI) in Seattle to ask for permission to marry Summer, who gets a vision of her future. And Kaitlin realizes that she likes Will (recurring guest star CHRIS BROWN), but she is concerned he thinks she's too shallow.

Che (recurring guest star CHRIS PRATT) and Seth take a trip to a forest, where Che has a dream and discovers that his spirit might be in love with someone unexpected. Afterwards, Seth and Summer finally speak for the first time since she rejected his marriage proposal. Meanwhile, Taylor decides that she can no longer associate with Ryan. Julie works her way back into Kirsten's life in the only way she knows how. And Kaitlin shuts out Will (recurring guest star CHRIS BROWN).

As the Cohens prepare for Kirsten's 40th birthday party, Kirsten gets some news that will change her life forever. Meanwhile, Julie is having a secret love affair--and Kaitlin is doing everything she can to stop it. While Ryan acts as if he doesn't miss Taylor, she visits a therapist who gives her some rules to live by. After Seth and Che's (recurring guest star CHRIS PRATT) plan to save Newport's groundhog goes awry, Che finally realizes that Seth is not his soul mate. And Sandy and Kirsten have surprises in store for each other.

As Valentine's Day approaches, Ryan worries that the pressure of the holiday will ruin his relationship with Taylor. Meanwhile, revelations from their pasts--along with a psychic's dire predictions--cause Summer and Seth to question whether or not they are destined to be together. Kirsten reminisces about her own history and decides to share a long-held secret with Sandy. Ryan begins to tentatively reconcile with his father, Frank (recurring guest star KEVIN SORBO), thanks to Taylor's meddling. And Julie must choose between Frank and the man whom Kaitlin wants her to marry.

Taylor eagerly prepares for her first real birthday celebration, but she frets over the fact that Ryan has still not told her he loves her. Even more concerning is the fact that she has secretly applied to and been accepted at Berkeley, the same school Ryan is going to attend. Summer helps Taylor come up with a plan to help Ryan express his feelings. Meanwhile, Kaitlin misbehaves outrageously in reaction to Julie dating Frank (recurring guest star KEVIN SORBO)--but Julie finds out there's more than just the usual Cooper rebelliousness behind Kaitlin's actions. Kirsten deals with more than her share of catty Newport women when she joins a yoga class. Summer wishes Seth were passionately interested in something, the way she is about the environment. And a powerful earthquake shakes Newport Beach.

In the aftermath of a major earthquake that cuts off power and communication between the Cohens and their loved ones, Seth must take over Ryan's role as the protector when Ryan is injured and the boys are stranded on a deserted road. Summer and Taylor worry about their missing boyfriends while searching for Summer's escaped pet rabbit--and the quake leads to an unexpected reunion for Taylor. Trapped in a ruined ice cream shop, the scared Julie and Kaitlin spend the time bonding and dealing with an amorous clerk--until they are saved by the only man in Newport for Julie. And Sandy takes charge of the frightened crowd in a damaged shopping mall.

In the emotional series finale of "The O.C.," Ryan, the Cohens, the Coopers and their friends build new lives, resolve lingering issues, face major decisions and undergo shocking personal transformations. No matter what happens or where they go, the members of this unique extended family all know that they will always have one another to turn to.