Jack Kilmer is not used to being interviewed.

It’s a brutally windy day in New York and the star of Palo Alto, Gia Coppola’s cinematic take on a collection of short stories by James Franco, is sitting comfortably in a suite at the Conrad Hotel. Well, he’s still wearing a heavy parka and fidgeting with the zipper between questions. He struggles not to garble his responses (“Definitely, like, acting is kind of like…[it’s] just been such…[I’m] kind of obsessed with it now.”), but loses his train of thought sometimes, trailing off with a shy grin and an apologetic “...and yeah.” For a kid raised by two famous actors (his father, you may have heard, is named Val and his mother is actress Joanne Whalley), promoting his big Hollywood debut, Kilmer is acting implausibly like a normal 18-year-old.

In fact, it’s his total un-Hollywoodness that landed Kilmer the lead role of Teddy in Palo Alto. Coppola, Francis Ford’s granddaughter, and Kilmer grew up together. “Our parents are really good friends,” he says, and the kids were often dragged to “random” family events. When Coppola, now 27, adapted Franco’s stories into a dark, emotional screenplay about a group of high schoolers grappling with sex, boredom, and impending adulthood, she quickly recognized some of Kilmer in Teddy. She asked him to read through the script with her and put Teddy’s lines into his own words, adding insight to “what it’s like being a 17-year-old, or a kid who skateboards.” Eventually, she suggested filming Kilmer reading the script. “And I guess that was the audition tape,” he says.

Kilmer talks about his new career like it’s a happy freak accident, but that downplays the formidable, raw talent he shows onscreen. His performance as Teddy is naturalistic and sincere; he’s alternately insecure, awkward, foolish, funny and fascinating. In a word: teenage. The authenticity of the characters in Palo Alto is rarely seen in glitzier high school movies—a fact not lost on actual adolescents like Kilmer, who only graduated last spring.

“You see these movies and, in the same scene, they go from, like, chugging beers to hooking up with the cheerleader and all this stuff, played by 30-year-old actors and you think, When is that gonna happen to me?” he says. “It’s not really that glamorous in Palo Alto. It’s just kind of, like, there and sometimes it’s sad. I think [the characters] are just bored and that can be very relatable.”

Emma Roberts plays Teddy’s crush, a studious, good-girl type named April who has an unhappy affair with her single-dad soccer coach (played, of course, by Franco). Nat Wolff nails the role of Fred, Teddy’s volatile best friend, and Zoe Levin, Chris Messina, and Val Kilmer also star, the latter making a memorable cameo as April’s perpetually stoned dad.

“It was pretty hilarious seeing him high,” Kilmer laughs. “He’s a funny guy.” Val affectionately refers to his son as “my boy Jack” on Twitter and keeps an enthusiastic record of Palo Alto magazine clippings and photos. But when it comes to advice, Kilmer says, his dad has only imparted wisdom that applies “to anything in life, really: Just breathe and be really honest and take a lot of risks and have fun.”

Kilmer shies away from the word “career” to describe his acting ambitions and maintains a decidedly chill attitude about his new fame—even as online tabloids dub him “the next Robert Pattinson.” (Kilmer looks embarrassed at the mention of the report; he doesn’t know Rob “Patterson” well enough to compare, he says.) He was making music and just starting to apply to colleges when he began filming Palo Alto, but two more film projects have already come up: Len and Company, co-starring Juno Temple and Rhys Ifans, and Aaron Baby Superfecta, opposite Elle Fanning.

If he feels any pressure to live up to his dad’s fame, he doesn’t show it. “With Palo Alto as the catalyst, I’ve surrounded myself with people that have kind of created a world where I can feel like I’m not gonna be judged for doing something that I want to do. Everyone who’s around me is really supportive, so I don’t see any reason to stop now.” He smiles again. “I’m not trippin.’”