Maj. William Cage, an officer who has never seen combat, is the "Media Darling" of the armed forces. That all changes when he is assigned to a unit going into combat an alien invasion that looks like it could wipe humanity off the face of the planet. Trying to reason his way out of it, he ends up being stripped of his rank, labeled as a deserter, and dropped off at the very place that he never wanted to be, the front lines of the battle. He quickly meets his fate when an explosive detonates under one of the aliens and he dies covered in the alien's blood. He then comes to at the very spot that he was dropped off. Now, caught in a time loop, he has to figure out how to help the armed forces defeat this foe before they take over the planet.