The movie starts out with Krillin, Vegeta, Gohan, Future Trunks, Master Roshi, and Bulma. All of a sudden a spaceship appears and lands in front of them. The people from the ship emerge and bow down to Vegeta. They are the saiyan survivors from Planet Vegeta. Their leader, Paragas, tells Vegeta of a new planet they have found as a substitute for planet Vegeta.
Meanwhile Goku and Chi-Chi are on an interview for a school Chi-Chi wants Gohan to go to. On the interview King Kai calls Goku to his little planet because he says the Earth is in grave danger. Vegeta then goes to the new planet with Paragas along with the rest of the gang. Back on King Kai's planet King Kai tells Goku of the legendary super saiyian that completely destroyed the southern galaxy and he's heading to the northen galaxy next.
The team arrives on New Vegeta and they hear word of the Super Saiyan so the team leaves to investigate with Paragas's son Brolly. While investigating they find a slave camp and land there. They find out that the saiyan's imprisoned them and they fight their slave masters. All of a sudden Goku teleports in and is hit by Krillin's punch.
Back in Paragas's quaters he tells of a comet coming near New Vegeta that will eventually destroy it. Back at the palace, Gokou meets Brolly and Brolly gets angry but Paragas calms him down using a special device. Later on Paragas finds out that meeting Goku again brought back Brolly's memory of the time Goku made him cry when they were born and the saiyian instinct in him. At night Brolly attacks Goku but Goku knows and defends himself. All of a sudden Brolly raises his power level and Goku finds out that he is the Legendary Super Saiyan but Paragas comes over and stops Brolly.
The next morning Goku tells Vegeta that Brolly is the LSSJ and Trunks tells Vegeta that the idea of New Vegeta was a sham. Paragas reveals his plan to kill Vegeta and his companions and take over Earth so he sends Brolly after them. Brolly breaks the device and goes all out. He turns into SSJ and Vegeta finally realizes that he is truly the Legendary Super Saiyan. He fights them while Paragas tells Vegeta his story when he and Brolly were killed but brought back to life by Brolly's power. Since then they vowed revenge on Vegeta and Vegeta Jr.(present time Vegeta). The fight goes on and all of a sudden Brolly fires a ki blast at the planet the slaves came from and "POOF!!" it was destroyed in an instant.
All the characters who have the ability to turn SSJ do so and continue fighting except Vegeta who is scared of Brolly. The whole team get thier butts whipped and Brolly powers up even more. Brolly then charges his ki and fires a blast at Gohan that would kill him but it is intercepted by another blast. It's none other than Piccolo to save the day! He gives everyone senzu seeds and the team is recharged. The comet nears the planet and Krillin and Kamesenin escape in the spaceship Piccolo came in. The fight continues and they still are getting beat up. Gokou charges up a kamehameha and shoots it right in front of Brolly but nothing happens. Meanwhile Vegeta gathers up the courage to right Brolly and goes after him.
Meanwhile Paragas sees a time to escape and hops in a spacepod but Brolly finds him and murders him. Goku is the only one fully awake and begins to fight Brolly. Piccolo then tells everyone to give Goku their power to help him so all of them do (except Vegeta). It still isn't enough to help Goku and they have almost given all their energy to him. The comet gets closer and closer and the planet starts to get destroyed. Goku is no match for Brolly and is hurt badly. If Goku keeps going he will surely be killed. He beg's Vegeta to give him power. Vegeta then gives Goku the power he needs to defeat Brolly. When Brolly is about to give Goku the finishing blow Goku stops it. All the energy is given to Goku and he defeats Brolly just as the comet destroys the planet and teleports the gang to the space ship.