After the events of the previous film, Goku, now married to Chi-chi and Gohan's father, is visited by Raditz, a brother he didn't even know he had and who reveals that they are from an alien race called Saiyan, and that Goku was sent to Earth to conquer the world. After Goku refuses to help carry out his plan for world domination, Raditz kidnaps his son Gohan, causing Goku to form an alliance with his old enemy Piccolo to save Gohan and prevent the Saiyans from invading the planet.
