"Everything is going to be fine" is the sort of comment horror buffs love to hear before six unfeasibly pretty pals descend into a warren of dripping caves.
Director Neil Marshall impressed with his werewolf-style horror Dog Soldiers but he's surpassed himself with this tale of chicks with picks versus subterranean mutants.
A group of gung-ho gals get together every year to test themselves white-water rafting, bungee jumping or any dangerous pursuit you care to name.
This time they're having a bash at potholing in a cave system deep below America's remote Appalachian Mountains (Scotland, actually). But guess what? They're not alone.
When a rock fall blocks their exit they're forced to search for another way out...but find themselves hunted down by an in-bred race of slimy predators.
This sort of thing has been done countless times before - think Aliens set in Cheddar Gorge - but Marshall executes it with such panache that it rises way above the competition.
Even before they've run into cave-dwelling cannibals, there's thrills aplenty as the lithe ladies wriggle through rock pipes and swing across vast subterranean caverns.
So when the hunters and the hunted link up, the scream-ometer is racked up another couple of notches as the suffocating claustrophobia is coupled with a visceral cat and mouse chase through the stalagtites.
To give your frayed imagination even less respite, Marshall has also introduced a rather nifty sub-plot involving a bit of marital jiggery-pokery between two of the girls.
It's not subtle... but who wants subtle when there's climbing axes to be buried into heads and heaving chests to be munched on by ravenous "crawlers".
Top-hole entertainment, you might say. And the best horror film to crawl along in a long while.