After the death of the planet Thundera which forced the forcing the ThunderCats to flee their homeworld and flee to Third Earth, The fleet is attacked by the Thundereans' enemies, the Mutants of Plun-Darr, who destroy most of the starships in the "ThunderFleet" which contained the Sword of Omens along with the Eye of Thundera. Though the Mutants damage the flagship, the power of the Eye drives them back. Now on Third Earth its been peaceful and Lion-O and his crew are relaxing