Two Ice Age kids are orphaned and left to survive alone in the wild after their parents are killed in a bear attack. Tusk and his sister, Flint, discover ancient cave paintings with a horrific warning and instructions on how to survive a deadly meteor headed their way. Tusk is a natural born leader and believes only he can warn others and lead the clans to the land bridge and the New World. Flint has secrets of her own and a plan with a woolly mammoth to unite the animal kingdom before their world is blown away.