The Descent (2006)

One year after a tragic accident, 6 girlfriends meet in a remote part of the Appalachians for their annual extreme outdoor adventure, in this case the exploration of a cave hidden deep in the woods. Far below the surface of the earth, disaster strikes, & there's no way out. The group splinters & each woman pushes on, praying for another exit. But there is something else lurking under the earth. As the friends realize they are now prey, they are forced to unleash their most primal instincts in an all-out war against an unspeakable horror - one that attacks without warning, again & again & again.