He-Man has lost control of his Power Sword...just as he’s forced to battle dozens of mutants and minions of evil from two worlds—Evil-Lyn, Slithe, Beastman, Jackalman and more! With only his bare hands for weapons, and with the Power of Grayskull never more vulnerable, will any man help He-Man stand against the forces of evil? Fortunately for Eternia, a new breed of heroes has arrived!
On Third Earth, Skeletor has just made a deal with the Spirits of Evil, they gave him Sword of Power and Mumm-ra, he would help them escape the Onyx Pyramid, in which they have been trapped. Skeletor then imbibes Mumm-Ra's essences and send his Evil Warriors and Mumm-Ra's Mutants out to take down He-Man.
The group of Evil quickly finds He-man but are soon defeated by the Master of the Universe. But then when He-Man believes he had won, Skeletor uses his new power to bring He-Man's power back to the Sword of Power. This changes He-Man back to Prince Adam who has a mortal wound, and Adam dies.
Skeletor believes to have won, when Lion-O and the Thundercats crash through the Pyramid demanding the Sword of Power back.