Sam Bell is nearing the completion of his 3-year-long contract with Lunar Industries, mining Earth's primary source of energy on the dark side of the moon. Alone with only the base's vigilant computer Gerty as his sole companion, Bell's extended isolation has taken its toll. He longs to return home, but a terrible accident on the lunar surface leads to a disturbing discovery that contributes to his growing sense of paranoia and dislocation so many miles away from home.