 The sportswoman Sarah loses her husband and daughter in a car crash, but she survives. One year later, her friends Beth, Rebecca, Sam and Holly, leaded by Juno, invite her to explore a deep cave in the mountains. When the expedition is about three kilometers underground, a rock collapses and blocks the access tunnel, trapping the group inside the cave. With limited supplies, they try to find a way out, but sooner they face a hunger and savage breed of predators.