Zak (Zack Gottsagen), a 22-year-old with Down syndrome, lives in a retirement home in North Carolina where his attempts to leave are thwarted by kindly (if exasperated) Eleanor (Dakota Johnson). With the help of his mischievous roommate (Bruce Dern), wannabe wrestler Zak breaks out and heads cross-country in order to track down his wrestling hero Salt Water Redneck (Thomas Haden Church). Along the way, he befriends Tyler (Shia LaBoeuf), a troubled petty thief who has fallen foul of local crabbers Duncan (John Hawkes) and Ratboy (Yelawolf).

With more than a nod to Huckleberry Finn, Zak, Tyler and eventually Eleanor, make their way down river on a raft.

Zack Gottsagen is the first Down syndrome lead in a hit summer picture and he more than holds his own against an extravagantly gifted ensemble. Everybody is note perfect. Dakota Johnson’s widowed carer carries a soft, unspoken sadness; Bruce Dern is a riot; Thomas Haden Church hasn’t been this impressive since Sideways, and most actors would require all of Henry V’s St Crispin’s Day Speech to communicate what Jon Bernthal can do with two seconds of brooding silence.

And then there’s Shia LaBeouf. Somewhere between the actor’s much-publicised legal troubles and his “He Will Not Divide Us” stand-off with 4Chan trolls, people seemed to forget what a remarkable artist he is. He’s terrific here, and there’s an unmistakable warmth and generosity in the chemistry between him and scene partners Johnson and Gottsagen.

Wrestlers, including WWE Hall of Famers Jake “The Snake” Roberts and Mick Foley, and a rapper (Yelawolf) round off the cast and add to the textured Americana.

The obvious parallels with Mark Twain’s best-loved creation are heightened by Nigel Bluck’s hazy, gleaming cinematography, a bluegrass-inspired score, and a grand magic realist flourish towards the denouement.

An auspicious first feature from writer-directors Tyler Nilson and Michael Schwartz.

Opens October 18th