If you've ever fancied a spot of potholing, you probably won't for much longer. At least, not if you should catch sight of The Descent. A creepy, claustrophobic little horror film, it will increase your appreciation of wide open spaces no end.

British director Neil Marshall's first film was the hugely enjoyable Dog Soldiers. That was a tongue in cheek werewolf movie that matched its scares with a healthy dose of black comedy. There's no such light relief this time, though. The Descent is one of the most relentlessly nasty chillers in recent memory.

Following a dreadful personal tragedy, Sarah's extreme-sports loving friends decide a potholing trip could be just the thing to speed her recovery. Embarking on their adventure in America's Appalachian mountains, the all-female group look set for a fun trip. But before long it all starts to seem like a very bad idea indeed. Lost and apparently trapped in an unfamiliar, precarious network of caverns, they slowly realise they're not alone. Soon their weekend break has become a desperate, bloody battle for survival.

Marshall tells his simple story with pinpoint precision. The scares are hard and nasty, the characters well sketched and the oppressive atmosphere simply doesn't let up. A cornerstone of many great horror flicks is the setting. Pick the right one and half the work is already done, whether it's The Shining's creaky old hotel or alien's isolated spacecraft. The Descent's pitch-black network of narrow tunnels and lethal sheer drops fits the bill perfectly.

The first hour is actually the strongest. Throughout it the story escalates into a panicky bid for survival, the women's situation spiralling quickly out of control. Of course, it doesn't hurt that the film taps into some primal fears darkness, claustrophobia, falling and drowning to name a few. All of this keeps the tension ticking over fiercely. In fact, one or two sequences may leave anyone with a fear of enclosed spaces manically hyperventilating. Like all the best horror films, there is a sense that anything could happen it never seems that a happy ending is guaranteed.

When the creatures are revealed, some of the scare factor peters out. Shadowy presences are, after all, more chilling than fully exposed beasties. But by then, the film has reached fever pitch, and the frantic struggle to escape gives things a brutal, adrenaline-fuelled boost.

The characters themselves are all well enough realised to add to the tension. There are no empty-headed scream queens here; instead, the cast are a group of intelligent women having to work together to survive. Sarah (Shauna Macdonald) and Juno (Natalie Mendoza) are particularly well developed, adding a few unexpected twists to what could have been a straightforward stalk and slash flick.

Those of a nervous disposition should be warned, though; this isn't a film to pull punches. By the end the caverns have (literally) run red with blood. In fact, the whole film is clearly designed to be a true horror movie; the sort that wants to leave its audience as gibbering wrecks. And if all that wasn't enough, it really is the worst advert for potholing you could ever imagine.