Lion-O has nightmares of Thunderian countrymen who were left behind on Thundera while he and the other ThunderCats escaped. Jaga tells Lion-O that the Thunderians survived Thundera's destruction and that they are alive and well on a deserted island somewhere on Third Earth. Lion-O and the ThunderCats set out to find the Thunderians, but so does Mumm-Ra and his followers. In the end, the Thunderians Lynx-O, Bengali, and Pumyra are made into offical ThunderCats and welcomed into Cat's Lair.