20,000 years ago, our planet is entering an Ice Age. All kinds of animals begin immigrating to the south, seeking warmer climates.

Sid, a sloth, a woolly mammoth named Manny, a sabre-toothed tiger named Diego, and an acorn-loving squirrel named Scrat are forced to become unlikely heroes.

The four reluctantly come together when they have to return a human child to its father while braving the deadly elements of the impending Ice Age.