Trunks returns from the future to train with Goku and Vegeta. However, he disappears without warning. Then, the mysterious Fu enters the scene, telling them that Trunks has been imprisoned on Prison Planet, a mysterious complex in an unknown location in the universes. The group searches for the dragon balls to free Trunks, but an endless battle awaits them! Will Goku and the others manage to save Trunks and escape from Prison Planet?