Lion-O has gotten ahold of the last jar of Thundersnaps - the best cookies Thundera had to offer! But a difficult to open cookie jar sends Lion-O and Cheetara chasing down the legend of Boggy Ben.

Barely escaping the sudden destruction of their home world, Thundera, Lion-O and the ThunderCats crash land on the mysterious and exotic planet of Third Earth, home to the evil Mumm-Ra and a bizarre host of other creatures and villains.