When a sabre-toothed cub strolls into Esme's Stone Age village, she enthusiastically adopts it as her own, and names him Seb. But when Esme tries to train Seb as her pet, he won't listen-even when she uses her very loudest voice. When it becomes clear that Seb doesn't want to be anyone's pet, Morris the mammoth wonders-could they all be friends, instead?