

Vultureman has got a brand new invention but there's one big problem: he stole the idea from Panthro! Oh, also Vultureman is using his invention to take over Third Earth. So, there are two big problems.
Fleeing the destruction of their home planet Thundera, Lion-O and the ThunderCats land on the world of Third Earth. But their enemies, the Mutants of Plun-Darr have followed them and it turns out Third Earth already has a Mumm-Ra problem.
Fleeing the destruction of their home planet Thundera, Lion-O and the ThunderCats land on the mysterious, dangerous, all-around awesome world of Third Earth! But their enemies, the Mutants of Plun-Darr have followed them and it turns out Third Earth already has a Mumm-Ra problem - can Lion-O learn the ropes of being a leader in time?