Sylvester Stallone’s grimacing killing machine, Rambo, became a symbol of jingoism in the Reagan era, applauded by many Americans and derided by others. Those with a queasy sense of irony even found him funny. In Son ofRambow (so spelled because of trademark difficulties), British writer-director Garth Jennings (The Hitchhiker’sGuide to the Galaxy) would have us believe that the bulletproof avenger was capable of liberating the human imagination and inspiring a generation of young filmmakers. If correct, could this help explain many of the crummy movies made since the 1980s?

Jennings, to be clear, seems to be pleading a special case. The youthful imagination under consideration belongs to Will (Bill Milner), an adolescent in ’80s England whose family adheres to a sect called the Brethren. An especially glum splinter from the Puritan tree, the Brethren’s prayer rooms are as dismal and uncomfortable as their theology; alcohol, movies and television form only part of the roster of prohibitions. Will’s mother, sister and granny go about with covered heads and frumpy long skirts. Dad is dead. Despite all efforts to keep the boy in line, grim regimens of deprivation, when imposed on individuals from without, can often result in push back and even outright mutiny. It must be said that the best-known ex-Brethren was the infamous exponent of sex, drugs and the occult, Aleister Crowley.

Will seeks release from his gray, overcast life in drawing, filling books with colorful magic marker fantasy and producing simple animation on rifled sheets of paper. He ventures into movies at the prodding of a schoolmate, Lee (Will Poulter), who wants to submit his homemade rendition of Rambo to the BBC’s Young Filmmakers Contest. While Will and his fellow congregants form a prayer line outside the local bijou, Lee is inside, eagerly devouring the latest brands of