If you can get past the fact that the film was precision-tooled for the quirky feelgood slot of the Sundance film festival; if you can forgive the glaring product placement and the nerd-gasm casting of Mark Hamill in a key role of a film about fan geekery, then there is a fair amount to recommend this solid feature debut.

A narrative that combines the domestic dysfunction of Yorgos Lanthimos’s Dogtooth with the unabashed movie-buff joy of Garth Jennings’s Son of Rambow or Michel Gondry’s Be Kind Rewind, this is a study of a very singular character, shaped – or scarred – by a unique upbringing.

Twentysomething James (Kyle Mooney, who also co-wrote the film) lives with his parents in an underground bunker, protected by an airlock from the poisoned atmosphere outside. His only connection with the world is through a lo-fi television series about the galactic adventures of a large bear. James is consumed with Brigsby Bear. It is his creed, his guiding principle. He pores over each VHS-taped episode to winkle out hidden meanings. Then suddenly, Brigsby is no more and James learns that everything he had been raised to believe is a lie. Wrenched from the only life he has known, he clings to the thing to which he has always turned for solace: a squeaky-voiced, human-size bear locked in an endless conflict with a malevolent, disembodied head that mocks him from the sky. He sets out to finish Brigsby’s adventures with an amateur feature film.

Where the film best succeeds is in creating a credible character who has been insulated from the world he now finds himself flung into. James’s mangled chewing of language is particularly effective: “Yes, I would like one of that,” he says, when offered a beer. Less persuasive, perhaps, is the way that naive oddball James is unconditionally embraced by hipster teens. And the way that the internet is portrayed as some kind of affirming virtual group hug rather than a venomous snake pit powered by cruelty and malice.