13. The Descent (2005)
Director: Neil Marshall
Stars: Shauna Macdonald, Natalie Mendoza, Alex Reid, MyAnna Buring, Saskia Mulder, Nora Jane Noone
In this slow-building horror sleeper, a group of women squeeze into an unexplored cave system on a bonding trip and find themselves trapped underground with bloodthirsty mole creatures. We're pretty sure it's a metaphor for girl-on-girl STD transmission during menstruation but we could be wrong.