In this third installment of the animated saga of a young brontosaurus and his pals, trouble has come to the Great Valley in the form of a meteorite. It fell just beyond the valley and now blocks the main water supply. As the land dries and thirst increases, the different species of dinosaurs who once coexisted peacefully become fractious. Suddenly Littlefoot and his friends are no longer allowed to play together. As bigotry and bickering increase, Littlefoot's gang decides that it's up to them to save the day. Since they went outside the valley in the last sequel, they know where water can be found, and though the Great Beyond is populated by tyrannosauruses and other carnivores, the youngsters know that they and their parents must take that risk in order to survive.