Distraught, confused, and half-wild with fear, Sarah Carter emerges alone from the Appalachian cave system where she encountered unspeakable terrors. Unable to plausibly explain to the authorities what happened - or why she's covered in her friends' blood - Sarah is forced back to the subterranean depths to help locate her five missing companions. As the rescue party drives deeper into uncharted caverns, nightmarish visions of the recent past begin to haunt Sarah and she starts to realize the...

A woman goes on vacation with her friends after her husband and daughter encounter a tragic accident. One year later she goes hiking with her friends and they get trapped in the cave. With a lack of supply, they struggle to survive and they meet strange blood thirsty creatures.