Diego, Manny and Sid return in this sequel to the hit animated movie Ice Age. This time around, the deep freeze is over, and the ice-covered earth is starting to melt, which will destroy the trio's cherished valley. The impending disaster prompts them to reunite and warn all the other beasts about the desperate situation.

With the impending ice age almost upon them, a mismatched trio of prehistoric critters – Manny the woolly mammoth, Diego the saber-toothed tiger and Sid the giant sloth – find an orphaned infant and decide to return it to its human parents. Along the way, the unlikely allies become friends but, when enemies attack, their quest takes on far nobler aims.