Annexation of the Planet Vegeta is passed on from galactic warlord King Cold to his son, Lord Frieza. King Vegeta, ruler of the Saiyans, believes his son, Prince Vegeta, is destined to liberate their race from Frieza and rule the universe. He learns of Broly, a Saiyan infant born with a power level exceeding that of his son, and exiles Broly to the distant Planet Vampa where he, along with his father Paragus, are stranded after their spaceships are damaged. Paragus vows to raise Broly to exact revenge on King Vegeta. Five years later, a low-class Saiyan warrior named Bardock grows concerned about Frieza’s wickedness and sends his infant son, Kakarot, to Earth. His fears are realized when Frieza destroys Planet Vegeta after learning of the legend of the Super Saiyan that he fears could one day appear to challenge him. The genocide of the Saiyan race occurs with only Broly and Paragus, Kakarot and his brother Raditz, Vegeta and his comrade Nappa, and Vegeta’s brother Tarble surviving the destruction.
Forty-one years later, Kakarot, now named Goku, trains with Vegeta. Bulma is contacted by Trunks, who informs her that six of the seven magical Dragon Balls have been stolen by Frieza’s soldiers who have come to Earth. Goku, Vegeta, Bulma, and Whis travel to an arctic region to find the seventh Dragon Ball before Frieza can retrieve it. Meanwhile, Broly and Paragus are rescued from Planet Vampa by Cheelai and Lemo, two low-class soldiers in Frieza’s military. They are brought to Frieza who recruits them to help him defeat Goku and Vegeta and the two groups come face-to-face on Earth where Paragus orders Broly to attack Vegeta.
Broly fights Vegeta and his power and fighting abilities increase throughout the battle to the point of seemingly besting the Saiyan Prince. Goku challenges Broly and manages to gain the advantage. Frieza responds by murdering Paragus, triggering the awakening of Broly’s latent Super Saiyan powers. Now a mindless brute, Broly overwhelms both Goku and Vegeta, so they trick him into attacking Frieza while Goku uses his instantaneous movement technique to travel to Piccolo who helps teach Vegeta how to use the Fusion Dance technique. After two failed attempts, Goku and Vegeta successfully fuse into Gogeta and return to the battlefield who dominates the fight until an infuriated Broly powers up even further into his Legendary Super Saiyan form. Broly regains the advantage until Gogeta assumes the divine Super Saiyan Blue form, allowing him to take the advantage in the battle once again. The two Saiyans clash even more violently, breaking through multiple dimensions before arriving back on Earth.
Gogeta defeats Broly and nearly kills him with a powerful energy blast but Cheelai and Lemo, who had formed a friendship with Broly, summon the eternal dragon Shenron with the Dragon Balls and use their wish to transport Broly safely back to Vampa. Frieza retreats, promising to return another time. Goku later meets with Broly, Cheelai, and Lemo on Vampa, wishing to be friends and providing them with various survival supplies, while also hoping to spar with Broly and offers to help teach him how to control his power.