In light of the Galactic Guardians' latest victory, Flogg leads the Evil Mutants and the entire Denebrian forces in their final battle against Primus.
He-Man and the Galactic Guardians celebrate their victory in the Games. After failing to blow up the Great Hall with a stolen astrosub that has a Transium Ore, Skeletor and Flogg take hostages with the condition of their release is that He-Man must face Skeletor in the Arena.
The Galactic Guardians and the Evil Mutants compete against each other in the Games. While the Evil Mutants win the first round thanks to some trickery, the Galactic Guardians work to turn the tide against them.
He-Man and the Galactic Guardians head to the planet Crelus to find the blacksmith Yolt to make weapons for the upcoming Games. Though Skeletor and Flogg have a plan to make Crelus make weapons for them and fool him into thinking that the Galactic Guardians are the bad guys.
The Galactic Guardians and the Evil Mutants get involved with a battle between two gigantic stars. When the battle is finished, both parties must fight each other.
Skeletor and Korac free some mercenaries and promises them a reward if they terrorize Primus. When He-Man tries to infiltrate them and gets caught, Ambassador Bimo becomes his unlikely rescuer.
Skeletor causes a meteor to head to Primus while Crita starts a large offensive against the Mytes. With He-Man busy dealing with the meteor, Mara is on her own defending the Mytes from Crita and General Nifel.
To cut off the supplies to Primus, Skeletor and Flogg hatch a plan to conquer the planets in the Tri-Solar Galaxy. The planet Danzig is their first stop as He-Man, Flipshot, and Ambassador Bimo come to Danzig's defense.
The Mytes and the Gleanons are still at each other. General Nifel and Crita have a plan to subjugate the Mytes. Now He-Man and Mara must help the Mytes and thwart the Gleanons' plot.
Slush Head and Staghorn discover a 1980s rock star on a desolate planet. When they take the rock star to Denebria to meet their fellow Mutants, Skeletor plans to use the rock star in his plot to destroy He-Man.
The Mutant Mothership is caught in a space storm. Displeased with Flogg's decisions, Staghorn persuades B.H. and Quakke into starting a mutiny.
An unbeatable gladiator champion named Dreadator is persuaded by Skeletor to fight He-Man. To prove that he is the best warrior in the universe, Dreadtor challenges He-Man to a duel.
Flogg has obtained some new laser cannons with their range being a threat to Primus. Now He-Man and the Galactic Guardians must infiltrate Nordor and destroy the cannons before it can be used on Primus.
While on a reconnaissance mission to Primus' moon, He-Man and the Scientists of Primus discover a plant species that is harmful to the Mutants of Denebria. He-Man harvests the plants and brings them to Primus in hopes that it can keep away the Evil Mutants.
Skeletor uses an intelligence amplifier given to him by Korac to enhance the intelligence of the Evil Mutants. Even when they succeed in overcoming He-Man, the Evil Mutants start being intellectually superior to Skeletor.
Skeletor uses an invention to get into the Dream Zone. When he attacks the internal device that maintains the concentrated subconscious that helps to protect Primus, He-Man must enter the Dream Zone to confront Skeletor.
He-Man gets a big fan in the form of an old lady named Melindra. When the Galactic Guardians go on a mission, they are unaware that Melindra has stowed away on the Starship Eternia.
During an event on Primus where different inventions are being shown off, Skeletor has Grr steal a cloning device. When He-Man works to reclaim the device, the Evil Mutants obtain his DNA sample which Skeletor uses to create a clone he calls "He-Slave" which he plans to use to defeat He-Man.
A large meeting of magic users is occurring on Primus. The Opague magician Ramlin is in attendance as he has a plan to steal everyone's magic.
The Galactic Guardians and the Evil Mutants remember their recent battle in the Quagmi Swamps. Each side recaps what happened during the battle.
Skeletor gets his hands on some anxiety gas which causes any males exposed to it to become trembling cowards and has an opposite on females. Now it is up to the females to defend Primus from the Evil Mutants.
He-Man is homesick for Eternia as the Sorceress of Castle Grayskull to send Teela to visit him. Meanwhile, Skeletor obtains a volume of a spellbook called the Encyclopedia of Evil and plans to obtain the entire collection with the help of Flogg, B.H., and Quakke while also taking Grot as a hostage.
Master Sebrian and Mara crash land in a remote area of Denebria. When He-Man arrives on Denebria to save them, he encounters some friendly Mutants who claim that they were once humans.
He-Man and Skeletor arrive on the planet Machina where its inhabitants are controlled by machines. While He-Man joins a resistance and fights for the independence of Machina's inhabitants, Skeletor has other plans.
Primus' sun withdraws out of regeneration behind a shell. This causes an ice age to break out as He-Man works to preserve all life on Primus.
The Galactic Guardians destroy Flogg's new giant laser canon, but it's wreck emits a green gas that threatens the shield around the planet Primus. Skeletor soon produces more of the gas to weaken Primus and even He-Man's sword is affected.
Using an image projector found on an asteroid, Skeletor disguises himself and the Evil Mutants as Professor Galactica's Interstellar Circus. They use this cover to kidnap the Scientists of Primus in order to have them work on the weapons found on the asteroid.
Skeletor steals the plans for a gravity generator and builds one of his own. He plans to use it to push Primus out of its orbit where its temperature change threatens all life on Primus.
Skeletor uses a brainwave detector to help him find He-Man. When Skeletor abducts a spaceship, He-Man is nowhere to be found.
Skeletor uses the Mind Lens to influence the human will. After causing damage on Primus, Skeletor wants to use the Mind Lens on He-Man.
A spaceship carrying a little girl arrives on Primus. He-Man and the Galactic Guardians are unaware that the little girl is actually a dangerous cyborg used by Skeletor in his plot to bring down the shield surrounding Primus.
The Evil Mutants have taken over the prison ship Gaolotia. When Caz and Drissi take an Astrosub and get baited to Gaolotia, Skeletor contacts He-Man telling him to come rescue them at Gaolotia. The Sorceress of Castle Grayskull contacts He-Man stating that Skeletor is having Gaolotia placed in the path of the comet Xenon.
Skeletor threatens to destroy Levitan if He-Man doesn't surrender. He-Man disguises himself as a Mutant Trooper to get close to Levitan while having a plan to retake Levitan and all of Primus with the help of the Galactic Guardians and the resistance. Though Skeletor will destroy Levitan anyway even if He-Man surrenders.
As the Scientists of Primus work on a way to deactivate the Zeps, Adam and Mara go to where Master Sebrian, Hydron, and Flipshot are being held and free them despite interference by Crita, Slush Head, and the Mutant Troopers. Afterwards, He-Man and Master Sebrian provide a diversion for Skeletor while Mara, Hydron, and Flipshot retake the Starship Eternia.
At the advice of Flogg, Quakke puts up bounty posters for He-Man's capture as the Evil Mutants and the Zeps look for him. He-Man frees some prisoners from Slush Head as they join up in his resistance. When Skeletor threatens a village, He-Man offers to surrender if they spare the village.
Primus has been taken over by the Evil Mutants and the Zeps. As He-Man and Mara have the key to the shield around Primus, Skeletor has captured Master Sebrian, Hydron, and Flipshot and sends B.H., Quakke, and Staghorn to find He-Man. Meanwhile, the Scientists of Primus work to find what makes the Zeps assume their monstrous forms.
Obtaining a painting from a man named Helm, Skeletor and Slush Head stow away on Captain Tipper's ship and heads to a cave in Primus's wastelands and uses a spell to bring the dragon in the painting to life to cause chaos on Primus. He-Man, Hydron, and Flipshot then work to defend Primus from the dragon and other Temperic Oil paintings that Skeletor brings to life.
Skeletor and Quakke find a crystal on Denebria that makes Quakke stronger. Quakke tests his new strength on He-Man, Hydron, and Flipshot during their trip to get oil for the Vasionic Resonator on Denebria and they are saved by Sagitar.
He-Man saves Grot's garden from an attack by Hoove and Karatti. Meeting Werban in the Oasis, Skeletor tricks him into lowering Onnor's shield of protection so that Hoove can lead the Evil Mutants to invade Onnor under the cover of a peace talk.
During his fight with He-Man, Slush Head destroys the Trithuseum generators on Primus that prevents its core from overheating. The crystals needed to help power the Trithuseum generators upon its rebuilding can only be found in Gorn City on Denebria. He encounters the trader Meliac who Skeletor uses in his plot to defeat He-Man.
The New Adventures of He-Man is an animated series which ran in syndication in the fall of 1990 while Mattel released the toy line He-Man, an update of their successful Masters of the Universe line. The cartoon series was intended to be a continuation of Filmation's He-Man and the Masters of the Universe series.