While Skrat the Saber Toothed Squirrel is still ineffectually trying to regain his precious acorn, the misfit trio of Manny the Mammoth, Sid the Sloth and Diego the Sabretooth Tiger have settled down in an isolated valley with numerous other animals. However, the trio discover that the ice wall surrounding the valley is barely holding back a massive body of water behind it and it's melting state threatens to break and flood the valley. With their one chance of survival being a boat at the other end of the valley, the trio follow the desperate exodus there. Along the way, they meet Ellie, a female mammoth who is convinced she's a opossum like her brothers. While the strange group continues the trek, they must learn to get along even as Manny struggles to find some connection to this strange female who may be the only other one of his kind.

As an additional marketing ploy a special "anti-cell" spot was created with Syd complaining to the audience about a ringing cellular phone. The same was done for Brother Bear (2003), Robots (2005) and I, Robot (2004).

Manfred:
So, still think she's the girl for me?


Sid:
Sure. She's tons of fun, and you're no fun at all. She completes you.

Revealing mistakes: When Scrat sniffs for his acorn, submerged under the ice, his saber teeth are clearly not modeled before he sinks them into the ice.

Written by Lionel Bart