Years after an alien invasion almost extinguished human mankind, refugee on a secret base on the Moon, three heroes decide to jump into a time travel in the desperate attempt to save the survivors but they don't know that the Sentinel is waiting for them.

Years after an alien invasion almost extinguished human mankind, refugee on a secret base on the Moon, three heroes decide to jump into a time travel in the desperate attempt to save the survivors but they don't know that the Sentinel is waiting for them.