The Z Warriors discover an unopenable music box and are told to open it with the Dragon Balls. The contents turn out to be a warrior named Tapion who had sealed himself inside along with a monster called Hildegarn. Goku must now perfect a new technique to defeat the evil monster.

Five years have passed since the fight with Piccolo Jr. and Goku now has a son, Gohan. The peace is interrupted when an alien named Raditz arrives on Earth in a spacecraft and tracks down Goku, revealing to him that that they are members of a near-extinct warrior race called the Saiyans.