Cert 15 86mins Stars 3

A fractious family Christmas becomes a bloody nightmare of intolerance and violence in this low budget British sci-fi horror which is an imaginative spin on TV’s Big Brother.

Sam Gittens and Neerja Naik star as Nick and Annji, who wake up to find themselves trapped by a mysterious hard black substance which has coated the outside of his parents’ unassuming house .

Though the clocks, phones and internet have stopped working, the TV starts broadcasting instructions which become increasingly less benign, with the captives assigned tasks, provided with props and punished with severe penalties for infringing of the rules.

Among the squabbling, panic and bravado of a mostly unsympathetic bunch of characters, there are occasional flashes of humour in the increasingly nightmarish activities.

The script twists the format of reality TV shows to examine our relationship to religion and the mass media, giving us an ending which sends out an agreeably grisly, condemnatory and satisfactory signal to us all.