After a space battle with the Mutants, the group escapes in pods and land near a White Pyramid. Inside they meet Mumm-Rana, who isMumm-Ra's exact opposite. Mumm-Ra arrives and places her under a spell to control her, after falling in love with her and noting her knowledge of magic.
These two now evil Mummies plot to destroy the Thundercats and rule third earth side by side as King and Queen. However Lion-Opevails, and the Thundercats manage to turn Mumm-Rana back to her good self, and banish Mumm-Ra once again.