Fritz, the little mouse, has found out a secret! The old oak, which is housing his family, will be cut down soon to make place for a new road. Alarmed, Fritz's great-grandfather Balthazar visits tree-spirit Big Cloud, who is living in the Oak. Big Cloud asks the wise owl Lu for advice. Lu, who lives in the tree top, is very upset about the planned devastation of their environment and promises to help. Working together, the tree spirits in the nearby forest and the other animals who live near the Oak, make up their mind to save the tree and prevent the roadwork. Is there a chance for them?
