Mumm-Ra summons Malcar, an ancient alchemist, to return from the dead. The alchemist returns old and weak, as he was when he died. Mumm-Ra takes him to the forest of youth to restore his youth and power. Malcar regains his powers, and uses them against the Thundercats. He transforms all the Thunderillium on the planet into Thundrainium.
Jaguara cannot work New Thundera’s Gyro on her own. The Thundercats order a robot to aid her in running the Gyro. Screw Loose, a robot who specializes in Gyro’s, comes to New Thundera. Mumm-Ra manages to mess up Screw Looses brain so he becomes destructive instead of helpful. The Thundercats must help Jagara get Screw Loose under control, before the entire planet is destroyed.
The dreaded Queen Rotunda of Rotundaland falls in love with Mario when she mistakenly drinks a love potion and tries to force him into marriage.
When the Marios buy some magic garbanzo beans they are lead up the beanstalk to face a Giant Koopa.
Enjoy this fascinating experience of watching Bob Ross bring these deep dark woods alive; incredible magic on a partial black canvas.
The Doctor and Ace discover a stone spaceship underneath Warmsley's archaeological dig while Mordred summons Morgaine to Earth's dimension.
Wily Kit and Kat, exploring New Thundera, stumble upon an Orb of Gold, and pick it up thinking that it is apart of their Heritage. Possessed by the power of the Golden Sphere of City, the ThunderKittens get greedy, and let the power of the orb overcome them. Mumm-Ra manages to get a hold of the orb, and his powers get four times more powerful. He gets so powerful, he destroys the Sword of Omens. Jar, the scrap metal collector reforges it for Lion-O. He gets so powerful that he challenges the power of the ancient spirits of evil. They lock him out of his pyramid until he surrenders the Orb to them. The spirits of evil let him back in, but destroy the Golden Sphere of City.
Roseanne tries her hand at telephone solicitation while trying to console Becky who had an embarrassing accident in front of the school council.
Wily Kit and Kat are constructing a well for the New Cat's Lair on New Thundera. The Thundercats on New Thundera receive a distress signal from Thunderian refugees trying to find their way to New Thundera. The Kittens are left alone with Snarf on at the New Cat's Lair, and Lion-O and Snarfer are out constructing an early warning device (I guess for weather purposes). The rest of the Thundercats seek out the refugees in space. When Wily Kit and Kat strike water, they accidentally unleash a monster that Jaga trapped in the underground lake centuries ago. Frogman, with aquatic powers, tries to sink the New Cats Lair. Lion-O however re-traps Frogman in his watery prison.
Our heroes think they are going to a benefit Spaghetti Dinner at the Linguini Empire Colosseum, but it's all a plot by the evil Emperor Augustus Septemberus Octoberus Koopa to feed the Marios to the lions.
Mario and Luigi disguise themselves as Riverboat Gamblers to rescue the Princess who is held captive on Captain Koopa's sidewheeler, "The Sinister Star".
The Ancient Spirits of Evil bring the Mirror Wraith to Mumm-Ra, and he disguises it as a child's toy. Mumm-Ra then intercepts a thunderian escape pod which carries in it a little girl. He gives the toy to the child (Leah), and leaves. She is rescued by the Thundercats, and goes into New Cat's Lair with the doll. The doll turns into the Mirror Wraith when left alone, and begins to destroy Cat's Lair, and the Thundercats have no clue where the evil Mirror Wraith came from.
Peggy wins a free health week with the healthiest man in Chicago, but ends up converting him to her lifestyle, and he drops dead.
Melody falls in love with a guest at the ranch. The gang helps her prepare for her date.
The Chipmunks overhear Dave suggesting that he would prefer Alvin to be a Gymnastic Pizza Twirler, Simon a Pogo Stick Tester, and Theodore an iguana trainer, and immediately start to pursue those careers.
Sunni learns the importance of keeping Gummi traditions when a giant reawakens thanks to her carelessness.
Tummi takes pity on Doctor Dexter, an unsuccessfull pharmacist, and decides to improve his concocctions with a shot of Gummiberry juice. Unfortunately, this new wonder medicine also attracts the attention of Igthorn, and without the knowledge of how to exactly replicate the formula, the Doctor is caught between a rock and a hard place.
Kevin Keene and his dog Duke have been transported to Video Land and asked to help defeat Mother Brain.