Using the power of the Medallion of Serpos, King Hssss transforms Snake Mountain into the mighty snake god, Serpos.
The Masters are called to Spelea, where they discover Lord Dactys and his warriors defending themselves from a Caligar attack.
Adam has a dream in which he sees a warrior similar to He-Man fighting both the Snake Men and Hordak, prompting him to journey to Castle Grayskull.
Queen Marlena's aircraft loses power and crashes over the Corridors of Lithos as power outages wreak havoc across the planet.
Having been revealed as a traitor, Evil-Lyn is being pursued by Skeletor and the Evil Warriors! Evil-Lyn's father, the Faceless One, contacts the Masters, asking them to help save a living being that Skeletor intends to sacrifice at the Pool of Shadows, which would unleash unknown evil forces on Eternia from the Forsaken Realm. When He-Man arrives, he is shocked to see that it is Evil-Lyn that Skeletor intends to sacrifice...
Having overthrown Snake Mountain, the Snake Men seek the power of the Elders.
In a desperate effort to stop the return of the Snake Men, The Masters of the Universe seek out the aid of the Evil Warriors. But Skeletor looks to capture the heroes when they arrive. As the forces of good and evil battle, Kobra Khan and Rattlor make their way to the Void within Snake Mountain, freeing their ancestral allies, Tung Lashor, Sssqueeze, Snake Face, and the Snake Men leader, King Hssss!
Teela finds herself drawn to a village called Pelleezeea, where she falls from her Sky Sled.
The newly formed Eternian Council arrives at the Royal Palace for their inaugural meeting. Knowing that this could dramatically alter the balance of power on Eternia, Skeletor puts Beast Man's suggestion of a serpintaur attack into action. When the Masters see the dragons flying overhead and learn that serpintaurs are being rounded up at Snake Mountain, they construct their own dragon army, the Dragon Walkers!
Outside Castle Grayskull, the Council of Evil and the Evil Warriors prepare to conquer.
To calm a young boy's fear, Fisto tells the story of how he went from villain to hero with the help of a girl named Rayna and her brave companions.
The Bendari, an alien race from a world with no evil, come to Eternia to pit their greatest representatives of good and evil against one another.
Skeletor imprisons Zagraz, the keeper of the comets, and tries to convince him to form an alliance.
Skeletor orders the Toy Maker to send his toys into the palace. Once the toys are inside the castle, they grow in size and overpower Man-At-Arms.
Count Marzo has been holding Mekaneck's son captive for years as he uses the boy's talent to serve as a distraction to cover his petty crimes.
Man-At-Arms, Teela and Orko are kidnapped while He-Man is distracted. At Snake Mountain, Evil-Lyn shrinks the three and suspends them in a cage.
Uncover the fabulous secret powers of Castle Grayskull in Season 1, Volume 1 (33 episodes) of He-Man and the Masters of the Universe!