Set after the events of Continental Drift, Scrat's epic pursuit of his elusive acorn catapults him outside of Earth, where he accidentally sets off a series of cosmic events that transform and threaten the planet. To save themselves from peril, Manny, Sid, Diego, and the rest of the herd leave their home and embark on a quest full of thrills and spills, highs and lows, laughter and adventure while traveling to exotic new lands and locations.

16-year-old Cassie Sullivan tries to survive in a world devastated by the waves of an alien invasion that has already decimated the population and knocked mankind back to the Stone Age.