Twenty-thousand years ago, Earth was a wondrous, prehistoric world filled with great danger, not the least of which was the beginning of the Ice Age. To avoid really bad frostbite, the planet's majestic creatures - and a few small, slothful ones - begin migrating south. The story revolves around sub-zero heroes Manny the mammoth (Ray Romano), Sid the loquacious sloth (John Leguizamo), Diego the sabre-toothed tiger (Dennis Leary), and a prehistoric combination of a squirrel and rat, known as Scrat who go on a comical quest to return a human baby back to his father, across a world on the brink of an ice age. Also starring the voices of Jack Black, Cedric The Entertainer, Goran Visnjic, Stephen Root, Diedrich Bader, Alan Tudyk, and Jane Krakowski.