Description: The astronaut crew of a space shuttle looks on in horror as they witness the violent destruction of the Earth. However, they are given a chance to change humanity's fate when a sympathetic alien sends them five years into the past. Their mission--find out who's responsible for the plot to destroy the planet. Can they deal with their own pasts while saving the world from the mysterious organism known only as "Leviathan?" Wikipedia: In episode one, they travel back in time five years to stop the world from exploding.