The first breakout movie of this year’s Cannes Film Festival is Andrea Arnold’s “American Honey,” which premiered to rave reviews. On Sunday, the cast—including Shia LaBeouf and newcomer Sasha Lane–appeared at a press conference for the indie, which follows a group of young kids that travel across the country hustling money by selling magazine subscriptions.

Arnold (who put Michael Fassbender on the map in “Fish Tank”) discovered her latest star on the beach during spring break. “She just came up to me,” says Lane, who grew up in Texas. “She just seemed really nice and was smiling. I didn’t know what she was talking about.” But Lane found herself immediately trusting the director. “I knew she was someone important and would take care of me. I knew it wasn’t going to be a porn scam.”

“Did you get porn directors?” Arnold asked back. “There’s a lot of suspicions when you go up to people.”

To prepare for the project, Arnold took a series of road trips across Middle America, where she met young people similar to the characters in the film. “I had some quite difficult times by myself and all that open wilderness,” Arnold said. “It did make me think what it’s like to be on these crews.” She drove through a tornado and visited a local drug store in a small town in West Virginia, where the pharmacists told her they were prescribing painkiller to senior citizens and antidepressants to young people.

LaBeouf also took a week-long road trip to get into the character. “I was going for details,” he said. “How the money comes in, how the money goes out.” He said he knew about small town America from his own upbringing. “Oh man, this is not new information,” he said. “In Bakersfield, where my father lived for a stint, the only thing there is prison. I’m part of the underclass. That’s where I came from.”

“American Honey” also features the hippest soundtrack of Cannes. LaBeouf first spots Lane’s character at a Wal-Mart to Rihanna’s 2011 hit “We Found Love.” Arnold reached out to the pop star directly to get the rights to the song. “I love writing, ‘Dear Rihanna,’” Arnold joked. “I had to write a few letters for the song, explaining what we were trying to do.” LaBeouf shot that scene on his first day, and he recalls the director telling him—“Hey, I need you to body roll to Rihanna in front of everybody.”

“It’s a little awkward,” LaBeouf said. “I didn’t like it.”

But perhaps the biggest surprise of the conference was that LaBeouf—after a series of performance art stunts (including wearing a paper bag over his head in public)—was on his best behavior, dressed in a suit and face cleanly shaven. When a reporter tried to bait him about the love scene in the film, LaBeouf coolly answered: “I don’t think I get hired for sex scenes, I promise you.”

Later, he talked about finding his character Jay in “American Honey” and tennis champ John McEnroe in an upcoming biopic. “Jay is me,” LaBeouf said. “And so is McEnroe. That’s it, man. I understand these people I empathize with them. I get it. You just turn things up, turns things down.”