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.
The film opens with a Saiyan Space pod flying through space and crash-landing on Earth out of which a wounded Saiyan crawls out: Broly, the Legendary Super Saiyan. The wounded Broly shouts out in frustation and turns into normal form. The place soon freezes, trapping him in it and he falls into a coma.
Gohan has been kidnapped! To make matters worse, the evil Garlic Jr. is gathering the Dragonballs to wish for immortality. Only then will Garlic Jr. be able to take over the Earth in order to gain revenge for the death of his father. Goku rushes to save Gohan, but arrives at the fortress just as Garlic Jr. summons the Eternal Dragon! Krillin and Piccolo try to help Goku, but their combined powers.
Not paying attention to his job, a young demon allows the evil cleansing machine to overflow and explode, turning the young demon into the infamous monster Janemba. Goku and Vegeta make solo attempts to defeat the monster, but realize their only option is fusion.
Dr. Gero's Androids #13, #14, and #15 are awakened by the laboratory computers and immediately head to the mall where Goku is shopping. After Goku, Trunks, and Vegita defeat #14 and #15, #13 absorbs their inner computers and becomes a super being greater than the original three separately were. Now it is up to Goku to stop him.
The evil Dr. Kochin uses the dragon balls to resurrect his mentor, Dr. Wheelo, in an effort to take over the world. Dr. Wheelo, his body having been destroyed by the avalanche that killed him fifty years before, desires the body of the strongest fighter in the world as his new vessel. Believing Roshi to be the world's strongest warrior, Dr. Kochin abducts Bulma and forces Roshi to surrender himself to save her. When Goku hears of their abduction, he goes to their rescue.
Jaga Bada, Mr. Satan's old sparring partner, has invited Satan to his personal island to hold a grudge match. Trunks and Goten decide to come for the adventure and Android #18 is following Satan for the money he owes her. Little do they know that Jaga Bada's scientist have found a way to resurrect Broly, the legendary Super Saiyan.
After defeating Frieza, Goku returns to Earth and goes on a camping trip with Gohan and Krillin. Everything is normal until Cooler - Frieza's brother - sends three henchmen after Goku. A long fight ensues between our heroes and Cooler, in which he transforms into the fourth stage of his evolution and has the edge in the fight... until Goku transforms into a Super Saiyan.