Plot

Littlefoot befriends with a mysterious, fun-loving dolphin-like creature named Mo, who is trapped in "new water" caused by heavy rain. The gang then goes on an adventure to the "big water" to bring Mo home.

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.—Rodned

When heavy rains create a mysterious "new water", Littlefoot sets off to explore the Great Valley. He quickly becomes friends with Mo the mischievous Ophthalmosaurus who has been isolated from his pod by the weather. When Littlefoot and friends get separated from their parents because of the Earthshake, they help Mo get back home to the Big Water, while avoiding a hungry pliosaur. On the way, Littlefoot and Mo discuss such interesting and see dangerous things like imaginary friends, the pliosaur, the concept of loneliness, and the true meaning of a brother.