Return to Thundera

Leo reist mit der Zeitkapsel zurück nach Thundera, bevor der Planet zerstört wurde. Dort trifft er auch seinen blinden Vater Claudus. Währenddessen bauen die Mutanten an einem Roboter, der die Festung der Katzen auf der Dritten Erde zerstören soll.

The Thundercats briefly show Lion-O how the time capsule they recovered from the caveman works. Curious to see more, Lion-O activates it during his night-time watch, and gets caught in its projection rays. The rays send him back in time to Thundera, just before the final tremor that destroyed the planet. Meanwhile, the Mutants have built an evil robot monster that is destroying Cats' Lair. Back on Thundera, Lion-O encounters his father, Claudus, and saves him from a Mutant attack. In return, Claudus gives Lion-O the plans to the robot that was attacking the Thundercats in his own time.

Los Mutantes liberan a un robot invencible mientras Lion_o accidentalmente viaja en el tiempo a Thundera luego de que el Ojo de Thundera reacciona ante la cápsula del tiempo. Allí conoce a su padre quien le entrega un pergamino que contiene un secreto para utilizar en contra de los Mutantes.