Buzz and Mira arrest Lardak Lurdak, a small-time criminal, for counterfeiting on Tradeworld. Just as they are taking him back to the ship, Tradeworld disappears behind them in a burst of white light, leaving no trace behind. It is revealed that Zurg has destroyed the planet with his latest weapon and demands that the Galactic Alliance surrender before more planets are destroyed. When Madame President refuses, Zurg selects his next target, which is none other than Tangea, Mira's homeworld.
The Space Rangers attempt to protect Tangea with a laser-web that will prevent even the smallest speck of space dust from entering the planet's atmosphere before Zurg strikes at noon. Mira reassures her father, King Nova, that they are on the case, but he is disdainful of receiving help from "monkeys in space suits" and expresses his disapproval in Mira associating with them. Mira is furious at her father's arrogance, but is shocked when their plan fails and Zurg's Planet Destroyer strikes again, wiping out Tangea.
The Galactic Alliance surrenders and Zurg is invited to Capital Planet. He is ecstatic at the opportunity to make his enemies grovel, but Commander Nebula tartly informs him that Buzz has been reassigned when the Evil Emperor asks about his whereabouts. In reality, Team Lightyear was secretly assigned the task of finding and taking down the Planet Destroyer. Buzz believes the Planet Destroyer is somewhere on Planet Z, but Mira insists that they have to go to the Pelegar System instead. She claims she can still sense her father, and all of Tangea, alive somewhere in the Pelegar System, but can't explain how, although it is somehow due to her mental powers. On a leap of faith, Buzz agrees, and when they reach their destination they find the Planet Destroyer. However, it fires at them and transports them to another dimension, revealing Tradeworld and Tangea and unveiling the truth behind Zurg's plans.
With the help of King Nova, he and Mira synchronise their powers and ghost through the Planet Destroyer's transdimensional hull. Mira takes down the Hornets that attack them inside, knocking out the two Brain Pods standing watch in the process. King Nova displays another aspect of Tangean mental powers and "sifts" or "fishes" through one of the Brain Pod's minds in order to glean information on how the Planet Destroyer's controls work. Mira is intrigued and asks him to teach her this skill after they return the planets to their original locations.
Back on Capital Planet, Buzz, Booster and XR confront Zurg just as the planets have been returned and the Senate erupts into cheers. Zurg escapes before he can be apprehended, and Buzz slyly tells King Nova to transfer Zurg's dreadnaught to the other dimension. Buzz thanks King Nova personally, and the monarch grudgingly admits that he wouldn't have managed this without their help, either. Mira successfully reads one of the Brain Pods' minds, acquiring a useful skill for future adventures with Team Lightyear.