Join your favorite animated prehistoric pals, Littlefoot, Cera, Ducky, Spike, Petrie, and shy newcomer Ali for another exciting adventure! A heard of migrating Longnecks has important news of weather changes in the regions beyond the great valley. What was once dry land has become "The Land of Mists.' Strange new creatures have begun to appear in these rainy marshes, while others have moved into the high trees that the Longnecks used to feed on. Fortunately, the Great Valley is as beautiful as ever. There's no need to brave the wetlands - until Littlefoot's Grandpa becomes ill. His one hope is to eat the healing petals of a golden Night Flower that only grows...in the Land of Mists! Now it's up to Littlefoot and his pals to explore the swamps, outwit sly new villains and find the Night Flowers in time to save Grandpa.