Fact1: Sarah and friends are reunited at cabin in Appalachian Mountains of North Carolina for spelunking adventure, Fact2: Juno apologises to Sarah for not being there for her after accident, Fact3: group comes across den of animal bones, Fact4: Beth begs Sarah to euthanize In pain and not wanting to be eaten by crawlers her, Fact5: Rebecca bleeds to death in front of Juno and Rebecca
Output: On her way back from whitewater rafting with her friends, Juno Natalie Mendoza, along with Beth Alex Reid, Sarah Shauna Macdonald, Sarahs husband Paul Oliver Milburn, and their daughter Jessica Molly Kayll get involved in a car accident when Paul is distracted. Paul and Jessica are killed, but Sarah survives. One year later, Sarah and her friends Juno, Beth, Sam MyAnna Buring, Rebecca Saskia Mulder, and newcomer Holly NoraJane Noone are reunited at a cabin in the Appalachian Mountains of North Carolina for a spelunking caving adventure. The next day, they hike up to a cave entrance and descend. While in the cave, Juno apologises to Sarah for not being there for her after the accident, but Sarah is distant. As the group moves through a narrow passage, it collapses behind them, trapping them. After a heated discussion, Juno admits that she has led the group into an unknown cave system instead of the fully explored cave system that they had originally planned to visit, and that rescue is, therefore, impossible. She then tells Sarah that she led them into the unknown cave in the hopes of restoring their relationship, but Sarah rebuffs her. As the group presses forward with hopes of finding an exit, they discover climbing equipment from a previous caver and a cave painting that suggests an exit exists. Holly, thinking she sees sunlight, runs ahead, but falls down a hole and breaks her leg. As the others help Holly, Sarah wanders off and observes a pale, humanoid creature drinking at a pool before it scampers away. Later, the group comes across a den of animal bones and are suddenly attacked by the creature called a crawler in the credits. Holly is killed: her neck ripped out before her body is dragged away. Sarah runs, falls down a hole, and is knocked unconscious. Juno, trying to prevent Hollys body from being dragged away, kills a crawler with her pickaxe and then, startled, accidentally stabs Beth through the neck. Beth collapses with Junos pendant in her hand, and a traumatized Juno flees while Beth begs her not to leave her. Sarah awakens to find herself in a den of human and animal carcasses, and witnesses Hollys body being eaten by a group of crawlers. Juno discovers markings pointing to a specific path through the caves. After regrouping with Sam and Rebecca, and realizing the crawlers use of sound to hunt, Juno tells them the markings she discovered may point to the way out, but she will not leave without Sarah. Meanwhile, Sarah encounters Beth, who tells Sarah that Juno wounded and abandoned her. Beth also gives her Junos pendant, which Sarah recognizes as a gift from Paul, realizing that Juno had an affair with Paul before his death. In pain and not wanting to be eaten by the crawlers, Beth begs Sarah to euthanize her. Sarah reluctantly does so by bashing her head in with a rock. Sarah then encounters a family of crawlers but manages to kill them all, becoming covered in blood in the process. Afterward, she has a psychotic breakdown. Elsewhere, Juno, Sam, and Rebecca are pursued by a large group of crawlers. When they reach a chasm, Sam tries to climb across but encounters a crawler scaling the ceiling. It rips her throat out, but Sam stabs it before she bleeds to death in front of Juno and Rebecca. Rebecca is then dragged back and eaten alive as Juno escapes. Juno encounters Sarah and lies to her about seeing Beth die. After defeating a group of crawlers, Sarah confronts Juno, revealing that she knows Juno had wounded Beth and left her for dead, and about the affair. She then strikes Juno in the leg with a pickaxe and leaves her to die as a swarm of crawlers approaches. Juno is last heard screaming as Sarah escapes. Sarah falls down a hole and is knocked unconscious. She awakens, manages to escape from the cave, runs to her vehicle, and speeds off. She pulls over to the side of the road and breaks down in tears. After a truck passes her, she opens the window, leans out and vomits. Upon reentering the car, she sees Juno sitting next to her and screams. She wakes up back in the cave, realising it was just a dream. Upon waking up she sees her daughter sitting across from her with a birthday cake. Camera zooms out as crawlers scream in the distance.