William is about to finish kindergarten and enter school. He is sad that he will have to say goodbye to his best friend at kindergarten. His parents try to downplay his concerns, but it only makes William frustrated. William decides to escape into the mystical Night Forest with his plush bear, Tjugga. In the Night Forest, they find Sally the fox, whose caterpillar pet was taken by a dragon. Despite his fear, William decides they must go on an adventure through a forest, sea, an island, and a mountain to reach the dragon’s cave and save Sally’s pet.