10 Worst Betrayals In Horror Movie History 

Neil Marshall's 2005 genre mash-up is part monster movie, part claustrophobic thriller. It's well written, well acted and well scary too.

Sarah, grieving for her daughter and husband, killed in a car accident a year prior, decides to go spelunking in the wilds of North America with five pals. When the cave tunnel partially collapses, they must find another way out but there's a problem - they are not alone. Pursued and attacked by multiple carnivorous, humanoid creatures, Sarah and the gang, now injured and desperate, must find a way out before they're picked off one by one.

Leading the group is Juno, the most experienced, yet paradoxically the most untrustworthy of the lot. It's revealed early on that she was having an affair with Sarah's husband at the time of the fatal car crash (betrayal number one) and to make things worse, she's led them into a previously unchartered cave system, so no chance of a rescue (number two).

As the creatures attack, Juno accidentally stabs Beth through the throat with a pick axe. Instead of helping, she leaves Beth to bleed out and returns to find the others (number three). When Sarah finds Beth dying, Beth reveals Juno's multiple betrayals - deceit, adultery and cowardice. Sarah must find her way out past not only the 'crawlers,' but past Juno too.

If crawling through pitch black, subterranean death traps seems an unlikely way to reduce your anxiety, you're probably right. Seeing the treacherous Juno left to the Gollum-Zenomorph-Type-Things in the film's superb climax is, however, a fitting end to a nasty piece of work.