An orphaned brontosaurus named Littlefoot sets off in search of the legendary Great Valley. A land of lush vegetation where the dinosaurs can thrive and live in peace. Along the way he meets four other young dinosaurs, each one a different species, and they encounter several obstacles as they learn to work together in order to survive.
A young mouse named Fievel and his family decide to migrate to America, a "land without cats," at the turn of the 20th century. But somehow, Fievel ends up in the New World alone and must fend off not only the felines he never thought he'd have to deal with again but also the loneliness of being away from home.
Captain New Eyes travels back in time and feeds dinosaurs his Brain Grain cereal, which makes them intelligent and non-violent. They agree to go to the "Middle Future" in order to grant the wishes of children in New York City. They are to meet Dr. Bleeb of the Museum of Natural History, but get sidetracked with their new children friends and run into the Captain's evil brother, Professor Screweyes.
