Using the power of the Medallion of Serpos, King Hssss transforms Snake Mountain into the mighty snake god, Serpos! Serpos begins to cause great destruction on Eternia, beginning with a vicious attack on the Royal Palace, then turning his attention on Castle Grayskull itself. He-Man and Zodak must combine forces to save the Masters and stop King Hssss from ruling all of Eternia!

As the Snake Men prepare to awaken Serpos, new trouple is already brewing in Eternia. Evil-Lyn has allied herself with Count Marzo, and together they head towards the Well of Darkness to free Hordak from Despondos! Learning from Kobra Kahn of Marzo's plan, King Hssss and his Snake Men must abandon Serpos - for a time - in order to prevent the release of Hordak. Caught between two forces of evil, He-Man and the Masters must make their stand against the Snake Men even while thwarting the release of the ancient leader of the Horde...

The Masters are called to Spelea, where they discover Lord Dactys and his warriors defending themselves from a Caligar attack. While King Randor mediates a truce between Lord Dactys and Ceratus, the Snake Men take advantage of the distraction to enter the Temple of Serpos, intent on awakening the Guardians of Old...

The Masters of the Universe have won a great victory in driving the Snake Men away from the Mystic Mountains. Entering a local tavern in search of rest and refreshment, Man-At-Arms comes face-to-face with his estranged brother, Fisto. Old grievances rise to the surface, and Man-At-Arms accuses his brother of being a deserter during the Great Unrest. But this moment is soon interrupted as Buzz Off and Stratos discover that Webstor has eaten Ambrosia and has transformed him into a large spider-creature with incredible power! When the Masters are trapped by Webstor, Fisto is called into action...

Adam has a dream in which he sees a warrior similar to He-Man fighting both Hordak and the Snake Men. Plagued by questions raised by this dream, Adam journeys to Castle Grayskull seeking answers from the Sorceress. The Sorceress answers with the story of King Grayskull. Meanwhile, events foreshadowed by the dream being to unfold as Hordak orders Skeletor to his former sanctuary, where he can free Hordak from Despondos....

The Masters of the Universe learn from Lord Dactys that King Hssss and his Snake Men are alive and well and are attempting to retrieve the powerful Serpent's Ring from the Sea of Rakash. Immediately, the Masters set off in pursuit, catching up with King Hssss and his henchment at the village of Felis Folia. With the Serpent's Ring now in his possession, King Hssss has already transformed the villagers into Snake Men, and does the same to the Masters when they arrive. It is up to He-Man, Roboto, and Orko to stop King Hsss form turning everyone on the planet into snakes!

When mysterious power outages wreak havoc across the planet, Queen Marlena's aircraft loses powre and goes down over the Cooridors of Lithos. Meanwhile, back at the Royal Palace, a being named Sortech has come to ask for help against an attack by Skeletor. In exchange for this aid, Sorteck offers a suit of Battle Armor. He-Man agrees to help the alien, sending Battle Cat to help King Rnador in the search for the missing Queen. He-Man and Sortech reach the alien's lair just as Skeletor, also clad in a suit of Battle Armor arrives to wreak his havoc...

Exposed for the traitor she is, Evil-Lyn now flees from Skeletor and his Evil Warriors! Realizing that Evil-Lyn stands no chance on her own, her father, the Faceless One, petitions the Masters for help. He tells of an unnamed living being by whose sacrifice Skeletor intends to unleash upon Eternia the untol evil forces trapped within the Forsaken Realm. Arriving at the Pool of Shadows to foil Skeletor's plan, He-Man is shocked to learn that this sacrificial lamb in none other than Evil-Lyn...