Early in American Honey, a teenage Texan named Star (Sasha Lane) gapes as a group of young people around her age take over the local superstore, hopping onto the bagging counters and clogging up the aisles as they gyrate to Rihanna's "We Found Love," which has just come on over the speakers. A security guard shows up to manhandle the kids out of the door, but no one seems to mind. It's just another spontaneous, temporary small-town moment of hilarity and celebration before the whole group loads back into a grubby van and heads for the next spot down the road. As they leave, one of the van kids, Jake (Shia LaBeouf), invites Star to come join them in Kansas City. She heads home, packs a bag, dumps the children she's caring for on their unwilling mother, and hits the road. She tells anyone who asks that she has a job, but she doesn't explain herself otherwise. That isn't in her makeup. Star isn't much of a talker, but growing up in extreme poverty, with a meth-addict mother and a sleazy young stepfather who gropes her, she's learned to grab anything interesting that's offered to her, without worrying about the strings attached.

Jake's invitation is the first offering she latches onto in the film, but it isn't the last. From the beginning, writer-director Andrea Arnold (Red Road, Fish Tank) invites audiences to wonder why Star is so rootless, so simultaneously demanding and easygoing, so stubbornly entitled, yet willing to roll with the flow. The bits of her history that emerge explain some of her character, but mostly, the film just watches her navigate enough situations that the logic behind the seeming contradictions gradually becomes clear. Her behavior initially seems erratic, but Star slowly emerges as one of the most startling and fascinating characters to hit movie screens this year. By the end of the movie's 158-minute runtime, she feels like an old friend — the kind that might steal your valuables and disappear in the middle of the night, but at least not unexpectedly.

Arnold's movie is immersive, and that's because she immersed herself in it, gathering a group of young people for a cross-country trip and letting them relax into their group dynamic until it felt natural. The van kids trek around the heartland selling magazines, and kicking most of the profits to their glowering manager Krystal (Riley Keough), who checks them into a different low-rent motel every night, and dumps them into a different neighborhood in a different city every day. Krystal's crew have widely ranging personalities, but all of them seem like lost kids, runaways and troublemakers who had a hard time at home, if they had homes at all. And one of Arnold's greatest accomplishments in American Honey is in illustrating, with a loose and comfortable storytelling style, how these misfits build a form of easy intimacy without really opening up to each other, or getting attached. They all recognize that their friendships are temporary, and that any of them could get kicked off the bus for underperforming, breaking Krystal's rules, or just annoying her. They're a sort of temporary family who live from party to party with a perfect willingness to share whiskey and weed, and to sing and dance together in those spontaneous dance parties. But any sense of loyalty comes second to their need to protect themselves from a world that's rejected them.

Star disrupts their natural order by instantly attaching herself to Jake, with a proprietary, aggressive resentment in place of affection. Their relationship is never romantic, or even real enough to give viewers a rooting interest. It's mostly a source of drama, as she blows up over any hint of affection he aims at another girl. Star is young and naïve, with her emotions close to the surface. She's easily angered, and prone to protectively withdraw into herself when her feelings get too strong. But she's principled, in a way her companions aren't, and her disgust at the idea of lying puts her directly at odds with Krystal, Jake, and their anything-for-a-sale philosophy.

The joy of American Honey is how easy, relaxed, and sprawling it feels, as Star gets to know her limits a little better, without any particular feel of a deadline, and no hint of artificially imposed narrative. The loose camera, the unhurried editing, and the attention Arnold pays to the seedy environments and the natural world all suggest a story with no agenda but character and mood development. The lengthy running time allows for plenty of incident, but also plenty of time to observe from a sociological remove. Threat hangs over the whole film — the threat of the unknown, of possible sexual or physical violence, of the various bad things that happen in movies to young people in poverty, with limited choices. But Arnold's film isn't about the action, it's about the state of mind that comes with youth, with travel, with a new relationship and an intriguing new way of living. Star never seems grateful to be invited along for the ride, but viewers should be. Her traveling companions offer intimacy without openness, but in a film this inviting and absorbing, intimacy feels like a real accomplishment.