When decorated soldier Captain Colter Stevens wakes up in the body of an unknown man, he discovers he's part of a mission to find the bomber of a Chicago commuter train.

With only three weeks left in his three year contract, Sam Bell is getting anxious to finally return to Earth. He is the only occupant of a Moon-based manufacturing facility along with his computer and assistant, GERTY. When he has an accident however, he wakens to find that he is not alone.