Full Synopsis: Forty-one years ago, the Saiyan homeworld Planet Vegeta is ruled the forces of King Cold, who delegates their command to his son Frieza. King Vegeta, leader of the Saiyans, believes his son Prince Vegeta is a prodigy destined to liberate their people and rule the universe. He learns of Broly, a Saiyan baby born with an abnormal power level exceeding that of his son, and exiles Broly to the distant planet Vampa.

Broly and his father Paragus, who goes after his son, are stranded on Vampa after their ships are damaged. Paragus vows to raise Broly as a mighty warrior to exact revenge on King Vegeta. Five years later, a low-class Saiyan warrior named Bardock becomes suspicious of Frieza and sends his son Kakarot (later named Goku) to Earth. His suspicions are confirmed when Frieza destroys Planet Vegeta after learning of a legend about a Legendary Super Saiyan who could one day defeat him. The Saiyan race is eradicated, except for Broly and Paragus, Goku and his brother Raditz, Vegeta and his comrade Nappa and Vegeta's brother Tarble.

In the present day, Goku and Vegeta train on an island with Bulma, Bulla, Beerus and Whis. Bulma is contacted by Trunks, who informs her that six of the Dragon Balls have been stolen by Frieza's soldiers. Goku, Vegeta, Bulma and Whis travel to the Arctic to find the seventh Dragon Ball before Frieza can retrieve it. Meanwhile, Broly and Paragus are rescued from Vampa by Cheelai and Lemo, two low-class soldiers in Frieza's army searching for recruits. They are brought to Frieza, who recruits them to help him defeat Goku and Vegeta. The two groups come face-to-face in the Arctic, where Paragus orders Broly to attack Vegeta.

Broly fights Vegeta and then Goku, growing stronger as the fight goes on and catching up to their Super Saiyan God forms. Goku overpowers Broly with Super Saiyan Blue and Frieza responds by murdering Paragus, triggering the awakening of Broly's Super Saiyan powers. He overwhelms Goku and Vegeta with his new power, so they trick him into attacking Frieza instead and then teleport to Piccolo's location. Goku and Piccolo teach Vegeta how to use the Fusion Dance technique; about an hour later, after two failed attempts, Goku and Vegeta successfully fuse together into Gogeta and teleport back to the battlefield. Gogeta turns Super Saiyan and engages in a beam clash with Broly, which shatters the fabric of reality and sends the two into another dimension. Gogeta dominates the fight until an infuriated Broly powers up even further into his Legendary Super Saiyan form. This allows Broly to regain the advantage, until Gogeta powers up into Super Saiyan Blue, allowing him to dominate the fight once again. The two then clash even more violently, breaking through multiple dimensions, before arriving back in the real world.

Gogeta defeats Broly and is about to obliterate him with a powerful energy wave, but Cheelai and Lemo, who had formed a friendship with Broly, summon Shenron with the Dragon Balls and use their wish to transport Broly 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 from Capsule Corp, while also hoping to spar with Broly again