The island trap works because it strips away the Tournament excuse and makes every punch mean something to people who never asked for a fight. Mr. Satan's desperation becomes the emotional center in a way the franchise almost never allows. Broly as a shambling bio-weapon loses the mythic weight that made him dangerous, but the movie knows it and pivots hard into visceral combat instead of pretending the story matters.

Mr. Satan gets an invitation from Jaga Bada, his former sparring partner, to settle an old grudge in a rematch on Jaga Bada's private island. Trunks and Goten decide to join him in search of adventure, and Android 18 follows Satan as well, intent on collecting money he owes her. None of them realize that Jaga Bada's scientists have discovered a method of reviving Broly, the legendary Super Saiyan. The result is a sci-fi action adventure film set on the island.