Eons ago, a man named Dyr created the Sunbird in order to overthrow the Council of Elders.
Unfortunately for Dyr, the Coucil discovered his plans, dismantled the Sunbird, and spread its pieces over the planet.
Thousands of years later, Skeletor means to reassemble the pieces and take over Eternia, enlisting the help of Evil-Lyn, Beast Man, and Mer-Man. But Zoar witnesses this meeting and alerts Adam while he is practicing with Man-At-Arms and Teela. He sneaks off and transforms into He-Man.
When He-Man arrives at Grayskull, the Sorceress leads him deep into the castle and shows him the Crystal of Knowledge, instructing him to put his hand on it. He does so, and learns the nature of Skeletor's plans and the danger they present to Eternia. He-Man then goes to the Royal Palace of Eternia and warns King Randor and the other warriors of the threat.Suddenly, word arrives that Avion is under attack. Stratos immediately leaves to protect his homeland, and He-Man, Man-At-Arms, and Teela each set out to stop Skeletor's warriors.
Stratos reaches Avion to find that Evil-Lyn is leading the onslaught with the help of ice dragons, herself riding one. Stratos outwits Evil-Lyn, causing her dragon to run into the mountain, but she transforms into Screeech and counterattacks. Her blast misses Stratos, but does reveal the location of a piece of the Sunbird. Just then, an ice dragon attacks and Stratos falls helplessly to the ground...
Meanwhile, Beast Man makes his way to the second piece to discover an ancient race of cat people worshipping the artifact. Beast Man takes control of them and begins to take the piece; however, Man-At-Arms has plans of his own and launches a surprise attack. Beast Man orders the cat people to defend him, though, and Man-At-Arms, outnumbered, is knocked unconscious. When he comes to, Beast Man dares Duncan to again try to take it. He does, but its animal protectors from the thicket move to stop him...
During all of this, Teela is heading towards the location of the third piece. She is attacked by some form of swamp creature, and is dragged underwater, but manages to escape before she suffocates.
A flying ship, managed by a clan of reptile men, net Teela and bring her aboard. Their captain is none other than Mer-Man.
Suddenly, a volcano erupts nearby, revealing the Sunbird piece. Teela uses the distraction to jump ship, remotely activating her Wind Raider, and flying to quickly claim it. But lava beasts stand to halt her adventure...
Finally, He-Man wanders the Sands of Time looking for the final part. A sand snake attacks, but He-Man cuts off its head. A sandstorm sweeps in and buries He-Man and Battle Cat. He-Man digs them out of it, only to reveal the final piece. Skeletor appears and uses the Havok Staff to summon a group of living skeleton warriors to stop He-Man, but the hero makes short work of them.
Skeletor, angry, summons the living skeleton of Dyr.
However, He-Man again defeats this foe easily by cleaving him in two and watching him crumble to dust. Infuriated, Skeletor summons a sphinx...
Triumphantly, Stratos breaks free and tricks the ice dragon into freezing Evil-Lyn, who falls to the ground. Man-At-Arms shoots the thicket creatures with his photon gun, burns them to the ground, and goes after Beast Man. Teela then tricks the lava beasts into killing each other, while Mer-Man uses the distraction to reach for the component.
Elsewhere, He-Man kills the sphinx with the Sword of Power.All the evil warriors touch their pieces at once and Skeletor gets both the pieces and the good guys!
The heroic warriors pass out and revive in a pit occupied by a huge monster -- the thing is, He-Man doesn't have the Sword of Power. But this proves to matter not, as they kill the monster, He-Man retrieves his sword, and he frees everyone. This, however, all proves to be a distraction, giving Skeletor enough time to reconstruct the ancient Sunbird.
There is a battle, while Duncan attempts to disable it. He is shot down by Skeletor, and Skeletor and his men leave as the Sunbird launches. He-Man leaps onto it and ends up stopping it. It crashes and skids to a halt just outside the palace. This wakes up Randor (it is the middle of the night), who sees the wreckage and orders Adam to clean it up.
It ends with Teela, Man-At-Arms, and Stratos watching Adam as he does so. Teela makes the comment that it is too bad that Adam doesn't have He-Man to help him. And they all laugh.