"Manfred" the mammoth is heading north just as just about every other critter is migrating the other way to avoid the harsh winter. Unfortunately for him, he encounters the sleepy-head sloth "Sid" whom he rescues from a pair of rhinos, only to bitterly regret his kindness as this pesky mammal is soon getting on his nerves. Meantime, a pride of sabre-toothed tigers are plotting revenge on a human village whose hunting parties have taken their toll on their now dwindling numbers. Their target is a baby - but luckily it's mother manages to plunge it off a waterfall where, drenched, it is rescued ...