They barely make it out of Thundera alive after Lion-O and the ThunderCats— Tygra, Panthro, Cheetara, Wilykat, and Wilykit— crash land on the fascinating and exotic planet of Third Earth. In his new role as Lord of the ThunderCats, Lion-O tries to guide the squad as they settle into their new planet. Mumm-Ra, Third Earth's dictatorial ruler, stands in the path of the ThunderCats, who must overcome a weird array of animals and adversaries, including the ThunderCats.