After fleeing their doomed homeworld of Thundera, and their fleet decimated and scattered by Mutants of Plun-Darr, the ThunderCats flagship, carrying their crown prince Lion-O, finds itself stranded on the distant world of Third Earth. Entrusted with the legendary Sword of Omens which contains the mystic Eye of Thundera, young Lion-O and his small band of survivors must contend with the mysteries of Third Earth, while keeping the Eye out of the hands of the Mutants, who have pursued them here and have awakened and allied with the ancient sorcerer Mumm-Ra the Ever-Living.
