It is the near future. Astronaut Sam Bell (Sam Rockwell) is living on the far side of the moon, completing a three-year contract with Lunar Industries to mine Earth's primary source of energy, Helium-3. It is a lonely job, made harder by a broken satellite that allows no live communications home. Taped messages are all Sam can send and receive. Thankfully, his time on the moon is nearly over, and Sam will be reunited with his wife, Tess, and their three-year-old daughter, Eve, in only a few short weeks.
Sarah is an autistic little girl whose father is worried about her health. Concerned for her, the father sees her removal from the hospital by force as the only option. An elevator breakdown prevents a smooth exit and leaves them trapped with others. Yet the incident is only the beginning of a descent into nightmare. As the doors open the hospital appears mysteriously deserted. When mutilated bodies are found, creatures from a dark world start a frightening attack. It soon becomes clear that the survival of the group may rest solely on the little girl.