No adult has ever been able to codify what separates a good movie from a classic. In kid terms, though—those favored by Son of Rambow, a chipper tribute to the cinema as both supplier and repository of dreams—a good movie merely sends you bounding home from the theater. A great movie demands some further physical response, like beaning your neighbor with a volleyball. And a classic? Simple. A classic makes you want to make movies.

Long ago, in the distant 1980s when Son of Rambow is set, "classic" wasn't the word anyone would have used to describe First Blood. A moody, proficient revenge thriller that heralded a coming wave of post-Vietnam sulking, it nonetheless begat Sylvester Stallone's segue from mush-mouthed punching bag to mush-mouthed killing machine. Watch First Blood, however, from the POV of a lonely, picked-on tween-age boy—i.e., the sensibility that pervades it—and it's a projector-beamed bolt from the blue. In that light, John Rambo looks like Mattel's own adolescent-angst action figure: ostracized, misunderstood by the world, preyed upon by authority figures, and best of all, unencumbered by girls. No wonder the misfit heroes of writer-director Garth Jennings's whimsical comedy—two enterprising British schoolkids who set out to make their own Stallone-derived fireballapalooza—feel less kinship to Indiana Jones, the keeper of covenants, than to Rambo, the army of one.

Introduced bootlegging First Blood at the neighborhood movie house, scruffy little hustler Lee (Will Poulter) has only the company of movies and a bulky camcorder. All but abandoned by his parents and mistreated by his caddish older bro, the conniving Lee takes a page from Rambo and passes along the hurt to someone else: a dreamy, repressed tyke named Will Proudfoot (the elfin Bill Milner), whose religion makes the sign of the cross against demon cinema. Lee has to cajole, bully, and guilt-trip his naïve new chum into top-lining his top-secret home movie. What it takes, ultimately, to make a believer of Will is a glimpse of Hollywood's forbidden fruit on Lee's VCR. The movie's cleverest, most exuberant sequence follows Will dashing home as his head buzzes for the first time with celluloid excess.

Jennings finds a tone here that's more winsome and less desperately wacky than his film version of The Hitchhiker's Guide to the Galaxy, especially as the movie-within-a-movie mutates into quirkily revealing psychodrama. Will and Lee's escape into cinema proves contagious, and the project—kids acting out the playground equivalent of fan fiction—quickly overturns their school's hierarchy of cool. Soon mousy Will is pogoing to the crazy new sound of Depeche Mode with a roomful of Space Dust–chugging hipsters—while Lee looks on miserably, hopelessly upstaged.

Their falling-out seems trumped up to provide last-minute conflict, as does the heavy-handed subplot involving the oppressive brethren of Will's church. But at its most likable, Son of Rambow evokes the rush of discovery that turns budding cinephiles into lifers—that delight in finding a film that seems to express or coalesce some inchoate yearning, including a yen to share.