The ThunderCats and Thunderians were two noble races that inhabited the planet of Thundera. Living a mutual life together, the two fled their dieing planet and settled on the world of Third Earth with the ThunderCats young king, Lion-O. Unfortunately, their long time enemies, the Mutants of Plun-Darr followed them to their new home and constantly attack them, led by the evil sorcerer Mumm-Ra. In an ever going search to find the all powerful Eye of Thundera, the forces of evil will stop at nothing to get at its power. Faced with the new threat, Lion-O has assembled a team of powerful companions to battle the forces of evil and to help create order on their new home...