Troubled teenager Adam is constantly bullied and threatened by his classmates at school, making his school life very unpleasant. By chance, he discovers letters between his mother and his supposedly "deceased" father in a hidden compartment at home, only to learn that his father is not dead but living alone in a remote, uninhabited primeval forest. Furious that his mother kept this secret from him, Adam angrily runs away from home and embarks on an adventurous journey to find his father. In the forest, Adam finally locates his father, but to his surprise, his father turns out to be the legendary "King of the Forest." Under his father's guidance, Adam gradually unlocks his wild talents—living in treehouses, sliding on zip lines, communicating with animals, running freely at incredible speeds, and teaming up with his father to master the jungle. However, danger lurks even in the happiest of times. A team of men in black invades the forest to capture Adam's father. To protect Adam, his father falls into a trap and is dragged away by a helicopter. Determined, Adam decides to join forces with the animal residents of the forest to rescue his father.