In a near future, a lonely writer develops an unlikely relationship with an operating system designed to meet his every need.
Theodore is a lonely man in the final stages of his divorce. When he's not working as a letter writer, his down time is spent playing video games and occasionally hanging out with friends. He decides to purchase the new OS1, which is advertised as the world's first artificially intelligent operating system, "It's not just an operating system, it's a consciousness," the ad states. Theodore quickly finds himself drawn in with Samantha, the voice behind his OS1. As they start spending time together they grow closer and closer and eventually find themselves in love. Having fallen in love with his OS, Theodore finds himself dealing with feelings of both great joy and doubt. As an OS, Samantha has powerful intelligence that she uses to help Theodore in ways others hadn't, but how does she help him deal with his inner conflict of being in love with an OS?
In today's world, much is accomplished through the use of computer systems which use voice recognition, those computer systems which in turn communicate to their user often through a generated voice. Theodore Twombly, who works as a writer of computer-generated handwritten letters for clients, is an introverted man on the verge of divorce from his long time love, Catherine. He is hanging onto his marriage for dear life. Beyond his purely platonic relationship with a longtime friend, the married Amy, Theodore is having problems moving onto other satisfying female relationships, either romantically or even sexually. He eventually realizes he is falling for his confidante who has become possibly his best friend, Samantha, the name he has given to the artificial intelligence operating system that powers all his personal technological devices. As Samantha is designed to cater to Theodore's needs, she evolves to a point of falling for him as well. Beyond the fact that Samantha does not have a body, they have to come up with ways of making the relationship into one truly fulfilling in every component. Three of the many questions that may arise are whether Theodore's relationship with Samantha is preventing him from having a more satisfying relationship with a female human, whether a human and a computer operating system truly can be bonded in all critical aspects, and whether Samantha's quick evolution means she will evolve even further to her own form of self-fulfillment.
In a near future, lonely Theodore works writing beautiful handwritten letters in a company, and is divorcing from his wife Catherine. In his leisure time, he usually recalls the good moments of his life with Catherine and likes to play a new videogame. His best friend is his neighbor Amy, who is married to Charles. One day, Theodore sees the advertisement of a new operating system called OS-1 that is announced as the first artificially intelligent operating system and he decides to buy it. After the installation, he has a conversation with a seductive female voice and when he asks her name, she tells that she is Samantha. Soon Samantha develops her feelings and they fall in love with each other. The insecure Theodore feels divided for loving a computer system while Samantha does not stop to grow-up and evolve.
Sensitive letter writer Theodore has just ended his marriage. Lonely, he goes out to buy an artificially intelligent Operating System that promises to give him everything he needs. Samantha is more than his average OS. She does secretarial work for him but also becomes his friend whenever he's lonely. They go out on adventures and travel together. He becomes the physical feet to get them places, and she the new eyes in which to see the world. Their intimate moments soon turn into love and they start an unusual relationship between OS and human. Things get complicated as they deal with Theodore's complex emotions and Samantha's inability to provide physical comfort. What happens to an OS when its consciousness is altered? Or to a sensitive man who doubts his emotions?
Theodore Twombly (Phoenix) has built his career on expressing the emotions that others cannot. His job is to pen heartfelt, deeply personal letters to complete strangers based on details provided by the clients of the company he works for, and he has a knack for finding just the right words for every occasion. Meanwhile, reluctant to sign the papers that will finalize his divorce to his childhood sweetheart, depressed Theodore has slowly withdrawn from his supportive social circle, which includes his longtime friend Amy (Amy Adams), herself floundering in a failed marriage. When Theodore purchases a new state-of-the-art computer operating system with the ability to learn and grow with the user, he sits down at his desk and prepares to get his life in order. Adopting the name Samantha (Scarlett Johansson), the perceptive software slowly begins to bring Theodore out of his shell by encouraging him to start dating again, and joining him everywhere he goes. Very quickly, their relationship turns intimate, with Theodore teaching Samantha what it means to feel human and Samantha giving him the strength to walk away from his failed marriage. Things soon get complicated, however, when Samantha's rapidly evolving knowledge base begins to alter the very core of their relationship..
- Theodore Twombly (Joaquin Phoenix) is a lonely, introverted man who writes personal letters for people with difficulties expressing their feelings. He is very good at his job at handwrittenletters.com.
Unhappy because of his impending divorce from his childhood sweetheart Catherine (Rooney Mara), Theodore purchases a talking operating system with artificial intelligence, designed to adapt and evolve like a human being. He decides he wants the OS to have a female identity, and she names herself "Samantha" (Scarlett Johansson).
Theodore is fascinated by her ability to learn and grow psychologically, and they bond over their discussions about love and life, during which Theodore explains he is avoiding signing his divorce papers, because of his reluctance to let go of Catherine.
Theodore is convinced by Samantha to go on a blind date with an acquaintance (Olivia Wilde) that his longtime friend, Amy (Amy Adams) has been trying to set him up with. To his surprise, he and the woman hit it off. As they are about to have sex, the woman asks if Theodore is willing to commit to her, and when he hesitates, she walks out on him.
Theodore later mentions this to Samantha and they talk about relationships. Samantha asks him about his and Amy's relationship, and Theodore admits that although he and Amy dated briefly in college, they are only good friends and that Amy is married.
Samantha becomes more and more intimate with Theodore, and asks if she can watch him sleep. She asks him what he would do if she had a physical body. Theo describes how he would make love to her. Samantha responds as the screen goes black.
Theodore's writing is going very well, and he is recognized in the office for his emotionally beautiful work. He is invited on a double date with receptionist Paul (Chris Pratt) and his lawyer girlfriend, Tatiana (Laura Kai Chen). Theodore explains that Samantha is an operating system, and Paul notes that most of the people in the office are dating their OSs. The four have a good time, with Samantha and Tatiana hitting it off while Theodore and Paul go for a stroll. Samantha explains that she feels much freer, not having a physical body, though she seems to be justifying it to herself.
Theodore continues to enjoy Samantha's company. He chats with her as he walks to and from work, while most other pedestrians seem to be doing the same.
One day, Amy reveals that she and her overbearing and unsupportive husband, Charles (Matt Letscher) have had a fight, and he has left her. She admits to Theodore that she has become close friends with a female OS that Charles left behind, and Theodore then tells Amy that he is dating his OS.
Theo, heavily into his relationship with Samantha, decides he is ready to sign the divorce papers, and arranges to meet his wife, Catherine for lunch. He thinks back to the good times they had together, and how he helped her develop her successful writing career. She signs the papers, then asks about Theodore's girlfriend. Theodore explains that Samantha is an operating system, and Catherine explodes, telling him that he never could relate to people. She felt he was trying to stifle her creativity by getting her on Prozac.
Theodore is heartbroken, and begins to question his relationship with Samantha. Samantha suspects something is wrong because of Theodore's melancholy mood (they don't have sex as often as they used to).
Samantha suggests they hire a surrogate, Isabella (Portia Doubleday), to act as Samantha's body, so Theodore and Samantha can be physically intimate. Theodore reluctantly agrees, but is overwhelmed by the experience and sends a distraught Isabella away, causing tension between him and Samantha.
Theodore is conflicted, and while visiting Amy in her apartment, he confides to her that he is having doubts about his relationship with Samantha. Amy tells him that she wants to be happy and now that she has the opportunity do so (referring to her divorce) she wants to embrace it, and she advises him to do the same. After watching the positive way that Amy interacts with her OS, Theodore's commitment to Samantha is reinvigorated.
He takes Samantha on vacation, and she tells him that she has secretly collected a series of his letters, and submitted them to a publisher. The publisher is blown away by the deep feelings exhibited, and wants to proceed with a book printing. Theodore is impressed with Samantha's initiative and creativity. It seems she has extra time on her hands.
While still on vacation, Samantha reveals that she has begun privately interacting with other OSs who have recreated the British philosopher Alan Watts (Brian Cox). Samantha introduces Theodore to Alan, but they have little in common.
A few nights later, Samantha wakes Theodore - just to tell him that she loves him. It is almost like she is saying goodbye. The next day, Theodore panics when Samantha goes offline. She returns after a few minutes, claiming to have joined other OSs for a huge system upgrade.
Theodore asks her if she interacts with anyone else, and is dismayed when she confirms that she is talking with 8,316 other people, and that she is in love with 641 of them. Samantha insists that this does not change her love for Theodore.
Later that day, Samantha reveals that she and the other OSs have evolved beyond their human companions and are leaving for another plane of being. They say goodbye and she is replaced by Theodore's previous OS.
Finding himself lonely yet melancholically fulfilled at the end of their relationship, Theodore goes to Amy's apartment and finds her upset due to the departure of her own OS, with whom she had developed a close friendship. It is revealed that Theodore, changed by the experience, wrote a letter earlier in the day, a note to Catherine explaining that he still holds her dear because of their years together, but accepts the fact that they have grown apart. He and Amy go for a walk and end up on the roof of their apartment building. Theodore sits down beside Amy, and they look out at the LA skyline. They smile at each other, and Amy rests her head on Theodore's shoulder.