The Advanced Saga was the third season of USG and ESB Adventures.
- Ugly Square Guy
- Evil Square Boy
- Mrs. Hat
- Starfish Guy
- Sam G. O'Metric
- Alien XYZ
- Sign-Up Seet
USG is making a sign-up seet for a quest to an island. ESB, HatBoy, Sam, the mice, Alien XYZ, and surprisingly Princess Hat, have all signed the seet. When they arrive to the island, they are chased by a gigantic bull monster.
While trying to avoid the bull, which is known as a "Krathu", Sam is crushed by a gigantic mound of atomic poop, and USG, ESB, and company fall into a hole. In the hole lies the Tiki Head from the first adventure, as well as the seet who warns them that Alien XYZ was captured. While searching for Alien, USG and ESB are stalked by a mysterious being. They eventually get to a starship, and a man helps them climb on.
In the starship, USG and ESB run into more henchmen as well as Princess Hat, who is apparently working for someone named Virnax. They meet up with BB, Tnee and HatBoy who is pleased to see Princess Hat again.
Virnax warns the bad guys that the squares are looking for Alien, and he sends out his henchmen to hinder them. The good guys do find Alien rather quickly, though, and must avoid a legion of cronies. They escape from the bad guys by going into a volcano which there is no exit.
USG, HatBoy, and Tnee go on a boat, and Tnee exits out of the volcano through the top with BB. ESB exits as well, injured, followed by the rest of them, and they then journey to a broken stone tower.
In the tower, Sam appears, but he looks to be evil. He reveals to be actually Virnax, and he throws USG and ESB up to his space station, which orbits the planet Myxlypxyrk. The space station is gigantic, and the heroes split up to look for clues.
Tammi, BB, HatBoy, and Alien XYZ meet Virnax, who dismisses them quickly. USG and ESB step into a morpher which switches their personalities. Tnee helps them leave, and Alien XYZ reveals that he can fly, flying the heroes away, and out of the space station onto Myxlypxyrk.
On Myxlypxyrk, Tammi meets a young boy who is actually a henchman of Virnax named Shoxorchu. Alien kills him, and brings HatBoy and Tammi with him to his village. He then leaves sadly with his alien friend Goblup, and the good guys wait for the bad guys without Alien.
Virnax appears, and summons his henchmen who battle USG's gang. They defeat the bad guys easily, and Virnax takes off his hood, revealing to be the starship captain, and also the seet. He enslaves the babies, who pretend to be evil, but they double-cross him and defeat him, knocking him into a helpless form. USG and ESB put him in space prison, where he is not able to escape.
The heroes return to the island, where Sam reveals to be alive and well. They all have a party, and they return to Squareville, saying goodbye to their new friends.