Twenty-thousand years ago, at the beginning of the Ice Age: many of the Earth's prehistoric animals
begin to migrate south to avoid the cold. But Manfred (Romano) the woolly mammoth,
likes to do things his way and decides to stay. And a terminally lazy sloth named
Sid (Leguizamo) also remains behind, and "adopts" Manfred as his protector. While trying to ditch
his annoying new "buddy", Manfred gets roped into helping
Sid reunite an abandoned human baby named Roshan (Strong) with his family. They are soon joined by a sinister
saber-toothed tiger named Diego (Leary), who befriends Sid and Manfred but secretly wants to devour Roshan.
As Manfred, Sid and Diego trek across the frozen landscape, a prehistoric squirrel/rat named Scrat
tries desperately to carry out his mission in life – to bury an acorn – which will trigger calamitous events.