Twenty thousand years ago, as the Earth was being overrun with glaciers, Manny the woolly mammoth, Diego the saber-toothed tiger, Sid the sloth, and the human baby Scrat become a courageous quartet braving the frozen terrain and embarking on an incredible journey to return Scrat to human civilization.

Scrat still desires to hold onto his beloved acorn, while finding a possible romance in a female sabre-toothed squirrel named Scrat. Having hooked-up, Manny and Ellie are expecting a baby. This leaves Manny anxious to ensure that everything is perfect for when his baby arrives. Diego is fed up with being treated like a house-cat and ponders the notion that he is becoming too laid-back. Sid begins to wish for a family of his own, and decides to steal...