When Littlefoot grandfather falls ill, The dinosaurs only way to cure him is a flower in the forbidding land of mist which hold unexpecting perils and danger.

When the dinosaur families get trapped in a valley by an ice storm, one family of "spike tail" dinosaurs volunteers to leave since they consume more food than the others. Meanwhile, the young dinos and a new adult dinosaur named Mr. Thicknose, head out to bring back their friend Spike, who has left his friends to be with members of his own species.

When heavy rains create a mysterious "new water", Littlefoot sets off to explore the Great Valley. He quickly becomes friends with Mo, a prank-playing dolphin-like creature who can't find his way back to the Big Water. Littlefoot and his pals come to the rescue and prove the value of courage, friendship, and diversity.