ThunderCats follows the adventures of the eponymous team of heroes, cat-like humanoid aliens from the planet of Thundera. The series pilot begins with the dying Thundera meeting its end, forcing the ThunderCats (a sort of Thunderean nobility) to flee their homeworld. The fleet is attacked by the Thundereans's enemies, the Mutants of Plun-Darr, who destroy all the starships in the "ThunderFleet," but spare the flagship hoping to capture the legendary mystic Sword of Omens they believe is onboard. The sword holds the Eye of Thundera, the source of the ThunderCats's power, which is embedded in the hilt. Though the Mutants damage the flagship, the power of the Eye drives them back, and Lion-O's elderly guardian, Jaga, volunteers to pilot the ship to the safety of the world of "Third Earth"; however, he dies in the process, because the journey to Third Earth took several decades due to damage to their ship. The flagship contains the young Lord of the ThunderCats, Lion-O, as well as the ThunderCats Cheetara, Panthro, Tygra, WilyKit and WilyKat, and Snarf.