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 it nuclear 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 the cats lair, and the other Thundercats. 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 destroying the Thundercats in his own time. ThunderCats (1985)