Danny takes the Tanners to Hawaii in honor of their two year anniversary since becoming a family. While there, Danny becomes his usual controlling self and takes the family around together, including on a visit to a deserted island where he forgets to tie the boat and it sails away. The family thinks they're doomed until they find out they are in fact on Pua Island where they meant they go for a show. Also Joey keeps seeing a hula girl he likes, and Jesse & Becky have an argument about Elvis.
From the Shadow Realm, the Shadowmaster contacts the Ancient Spirits of Evil (ASOE), telling them of how he captured Lion-O's father, Claudus, just before Thundera blew up. Then the Shadowmaster, through a bad dream, shows Lion-O his captured father and challenges Lion-O to a fight. Lion-O goes to the Shadow Realm through the Book and Sword of Omens, and is able to fight the Shadowmaster as long as the Sword stays bonded to the book. However, the Shadowmaster sends a huge bat to steal the Sword. It succeeds, and then Lion-O becomes very weak in the Shadow Realm. Mumm-Ra meanwhile, feeling like the ASOE will turn against him in favor of the Shadowmaster, sends Ma-Mutt to secretly steal the sword from the bat and put it back near the book. This renews Lion-O's strength, who calls for the Sword, rescues Claudus, and exiles the Shadowmaster. Claudus leaves Lion-O, but at the end you see him and Jaga standing next to each other in that blue, ghostly form. Now Lion-O has 2 mentors to give hi
Following the showdown in Europe, Ewing Oil and Weststar begin a new battle. Cliff is preoccupied at work. April's sister, Michelle, shows up in Dallas. Tommy returns home and attempts to make amends. Miss Ellie starts a search to find what the key in Jock's card opens.
Tommy claims to be a changed man as he plots revenge against Bobby. Cally's paintings manage to impress a gallery owner. J.R. makes a risky deal without Bobby's knowledge. Cliff manages to locate Afton. The mysterious key sends Miss Ellie and Clayton to New England. J.R. meets April's sister.
When Larry finds out that Grant, a co-worker of Jennifer's, is impressing Jennifer by raising money for a "Big Brothers" roller skating marathon, he gets jealous and lies about his roller skating ability to win Jennifer.
Instead of attending summer school, Hobie decides to go power skiing with two friends, whose recklessness leads to a tragic accident. Eddie's lack of financial resources is revealed when Craig finds him sleeping in one of the lifeguard towers.
When the handsome Prince Facade shows up in Hyrule, Zelda cannot keep her eyes off of him, and Link is green with jealousy.
Mother Winslow moves in and immediately begins to usurp Carl's authority. Eddie wants to go out with his friends, but he has a strict curfew that complicates things with Carl.
The Marios finally find a way back to Brooklyn -- and are faced with a big decision when Koopa captures the Princess just at the moment they can return home.
The Beagle Babes, female cousins of the Beagle Boys, kidnap Webby in ransom for a set of crown jewels.
Dwayne and Whitley run into each other on a flight back to school. Whitley finds that Dwayne has changed over the summer, as he is dressed in an expensive suit and seems to have matured during his successful internship at Kinishewa. Dwayne comforts Whitley when the plane experiences turbulence. Whitley kisses Dwayne in front of her entire dorm, prompting much teasing from her friends. Each insists that they are only friends. Whitley goes to Dwayne's apartment to see him, but is turned off when she finds him dancing like an idiot at a party. The residents of Gilbert Hall struggle to adjust to the fact that the dorm is now coed. Walter is the resident director, with Jaleesa as resident assistant.
Just as Rebecca fears for her sanity because of the erotic dreams she's been having about Sam, multi-millionaire Robin Colcord sweeps her off her feet.
Mumm-Ra has a new device, the Babylonian Barbarian Boiler, that he plans to use on Cats Lair. Ma-Mutt fools around too much and Mumm-Ra banishes him from the Pyramid. Later, the Thunderkittens, Snarf, and Snarfer bring Ma-Mutt back to Cats Lair and then Mumm-Ra fires the Boiler's beam at the Lair, which causes it to start melting. Snarfer makes a communicating device (because Ma-Mutt was trying to tell them about the beam), so they can understand Ma-Mutt. Ma-Mutt starts telling them of the Boiler, but Mumm-Ra sees this and through the Cauldron's magic brings Ma-Mutt back to the Pyramid. Then the ThunderCats construct a giant Light-Shield and use it to protect the Lair, but Mumm-Ra just boosts the power on the Boiler, destroying the Shield. Lion-O uses the Cat Signal to push back the beam, which causes the Boiler to explode, and the Signal restores Cats Lair. Mumm-Ra, who was lonely without Ma-Mutt, welcomes his dog back to the pyramid
Denise returns from Africa, with a new husband and stepdaughter in tow. Joseph C. Phillips and Raven-Symoné join the cast as Martin and Olivia Kendall. Last appearance of Peter Costa as Peter.
The Brigadier rescues the Doctor from the stone spaceship before they set out to locate Morgaine before she gains Excalibur.
Tygra, on a solo trip to New Thundera to meet the other Thundercats, decides to take a shortcut through a meteor shower. His ship is damaged, and he lands on an unexplored region of New Thundera. The Moss-Land. It turns out that the moss in moss-land is part of a giant monster who captures Tygra with its moss. Lion-O and Panthro set out to save Tygra and battle the Moss Monster.
McMurphy and K.C. are kidnapped by the Viet Cong and taken underground into a warren of tunnels, where their captors expect McMurphy to operate on their wounded leader.
Mario, Luigi, The Princess, and Toad hack their way through the Ama-Zone Jungle searching for Sheldon the Witch Doctor, but Koopa gets to him first.