Bill Milner stars as Will Proudfoot in Son of Rambow.

AP / Maggie Ferreira

Amateurish and small, Son of Rambow was the inexplicable hit of the Sundance Film Festival.

I don’t know. Maybe it’s that everything else was so bad that a little film about the unlikely friendship between a bright misfit boy and a mischievous school bully who partner on a homemade action movie was just too precious to ignore. Maybe the twin themes of the out-of-step boy and moviemaking appealed to movie fans who saw something of themselves in the film.

Yes, the boys make their movie despite having to hide it from the prying eyes of the puritanical religious sect the misfit boy’s family belongs to. And yes, the boys unsurprisingly solidify their friendship despite rocky moments. But their completed film within the film looks like what you might expect from a group of 10-year-olds, complete with characters wearing tin cans on their heads. And the overall movie itself, badly acted for the most part as it is, is only a step above that.

Son of Rambow was written and directed by Garth Jennings and produced by his partner Nick Goldsmith, who made a name for themselves with the offbeat The Hitchhiker’s Guide to the Galaxy. It’s set in the early 1980s in a small town in Britain. Young Will Proudfoot (Bill Milner) knows little of contemporary life because of the strict teachings of The Brethren. He has never seen a movie or television. The Brethern picket outside the local theater when it shows First Blood, Sylvester Stallone’s first outing as the fearless survivalist Rambo. Whenever a science documentary is shown in Will’s classroom, he sits in the hallway until it’s over.

Will’s life changes dramatically when he meets the devilish school bully, Lee Carter (Will Poulter). They form an unlikely alliance after Will is mesmerized by Lee’s pirated copy of First Blood. A new world opens up to him. Soon Will joins Lee in making their own action epic patterned after First Blood, with the previously shy Will in the Stallone role as “Son of Rambow.” They hope to enter it in a local TV competition.

This quirky little film ratchets up the quirkiness into outlandishness with the arrival of Didier Revol (Jules Sitruk), a foreign exchange student from France, who patterns himself after Prince. He wears a red leather jacket and high red boots, with a white streak in his hair, a hint of a tiny mustache and an ultra-cool attitude. Like an ’80s Pied Piper, Didier quickly becomes the idol of a group of dowdy British schoolboys and the star of Will and Lee’s movie.

Of course, Son of Rambow is about trying to fit in and friendship and bonding. Jennings has created a kid’s-eye view of the world, but in such over-the-top ways that it seems contrived and calculating, right down to Lee’s lay-about older brother whom Lee idolizes, but with little recognition in return. Little of it is believable. Some of it is painful to sit through.

**Son of Rambow

Starring: Bill Milner, Will Poulter, Jules Sitruk.

Rated: PG-13, contains violence.