A Dangerous Union

At Mount Paozu, Trunks arrives at Goku's home badly beaten, warning everyone that Android 17 attacked him. A strange hole appears in the sky, and King Kai contacts Goku to explain that Earth and Hell are being linked through a dimensional warp. The Z Fighters prepare for battle as citizens across the planet flee in terror, with King Furry struggling to keep order.

Android 17 sits alone on a mountainside, receiving strange mental transmissions telling him that another version of himself exists, separated by time and space. In Hell, Dr. Gero and Dr. Myuu celebrate their partnership. Gero reveals that a small probe he built was able to slip through dimensions and attach to the original Android 17, granting them remote control over him.

Trunks recovers and relays Android 17's message: Goku must go to Hell, or Earth will be overrun by its worst villains. True to the threat, waves of old foes pour through the rift. The Red Ribbon Army, General Rilldo, Frieza's soldiers, and many others begin attacking cities. Goku decides to go alone, eager to see whether Cell and Frieza have gotten any stronger.

On Earth, Goten tangles with Babidi's old henchmen Pui Pui and Yakon before Trunks steps in to help. Together they destroy Android 19. Pan handles the Red Ribbon Army soldiers chasing Mr. Satan, dispatching them with a single blow.

Goku descends into Hell and finds the prisoners bound up. Dr. Myuu and Dr. Gero greet him and send Hell Fighter 17 to attack. When Goku proves stronger than expected, the two doctors flee through the portal and seal it behind them, trapping Goku in the underworld with Super Perfect Cell and Frieza.

Back on Earth, the Z Fighters watch the dimensional rift vanish and realize Goku has no clear way home. Mr. Satan remains confident that Goku will find a path back, but the situation grows dire as the doctors roam free with their android creation and an army of resurrected villains at their disposal.