Set during the Ice Age, a sabertooth tiger, a sloth, and a wooly mammoth find a lost human infant, and they try to return him to his tribe. Back when the Earth was being overrun by glaciers, and animals were scurrying to save themselves from the upcoming Ice Age, a sloth named Sid, a woolly mammoth named Manny, and a saber-toothed tiger named Diego are forced to become unlikely heroes. The three reluctantly come together when they have to return a human child to its father while braving the deadly elements of the impending Ice Age.