Following from the first movie, Littlefoot, Cera, Spike, Ducky and Petri are living happily together in the Great Valley; however trouble is not completely absent with two egg-eating struthiomimuses about and the natural hazards of the valley itself. However the idyllic valley cannot stop the friends from becoming fed up with the grownups giving them lectures and restrictions because ‘they’re too little.’ They decide to show the adults that they’re not babies by giving chase to the two egg-eaters after seeing them in the act of stealing an egg; however in their pursuit the group cause a rockslide, opening the valley to the Mysterious Beyond. When the kids bring back an egg, they find that it is not the original; which is safe back in its nest. The friends decide to look after this new egg themselves, but when the egg hatches it reveals a baby sharptooth which Littlefoot befriends and names Chomper. Not long after the others befriend Chomper… but what to do with him?