This postapocalyptic survivalist thriller, set in rural Britain, is both violent and depressing, with some iffy line-readings, weird script moments and untied plot strands. It isn’t badly shot by any means, with one or two effective action scenes and interesting use of remote locations, but it takes two ploddingly long hours to tell a cumbersomely inflated and often dull story, which even at the finish line has to be wound up pretty arbitrarily.

We are in a lawless, chaotic land where food, water and shelter are grimly scarce. A lone individual (Luke Hobson), haunted by his tragic past, makes common cause with a young woman (Georgie Smibert) and a desperate, angry man (Chris Kaye) to win out against a terrifying band of marauding cannibals and rapists, led by a brutal figure known as The Beast (Bryn Hodgen). They also get help from a couple, played by Nicholas Chambers and Susan Lee Burton, who have their own reasons for fearing and hating these evil monsters.

The strangest moment comes when when Smibert’s character is briefly imprisoned as a sex slave by the Beast, and she briefly befriends another young woman chained up for the same purpose. Later, the couple reveal their daughter was taken and could still be in the Beast’s compound. Did these two plot points have a relationship in earlier script drafts? The way they played out here is disconcerting and inconclusive.

The story is, of course, headed for a monumentally horrible, medieval-style bloodbath, and the film delivers on that score, but the dialogue scenes are leaden and it is impossible to feel any sympathy or interest in any of its characters.

• Edge of Extinction is available on digital platforms.