An astronaut (Sam Rockwell) nearing the end of a three-year stint on the moon begins to experience strange delusions.

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.

His only link to the outside world comes from satellite messages from his wife and young daughter. 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.