After the destruction of the Venture compound after the climactic episodes of the previous season, the family is forced to move into a swank new living space.
Billy and Peter race to the rescue after St. Cloud steals their magical red ball. Meanwhile, Dr. Venture has to cure Pirate Captain of his tranq addiction to get his help saving Ven-Tech, Monarch and Henchman 21 set out to eliminate Monarch's arching rivals, and Brock and Hatred join forces to repel an invasion.
Dr. Venture tries to come up with a new super-science project with the help of Billy and Pete. Thanks to Dean's urethra, he thinks he has the solution. Meanwhile, Dr. Mrs. the Wife invites her husband to a combination Council meeting and 18th birthday party, unaware that it's a trap to discredit the Monarch with the Guild.
The Monarch decides to take on his father's legacy and become Blue Morpho so he can take out the villains arching Dr. Venture. However, things go terribly wrong. Meanwhile, Dr. Venture, Billy, and Pete try to develop mind-control gas, and Hank asks Brock for kissing tips.
Things go from bad to worse as Dr. Mrs. the Wife demands that Rusty show her the surveillance video of Haranguetan's death. He refuses, and an encounter with the new Blue Morpho convinces her that the new vigilante is... Rusty.
Hank takes Sirena on a date, and Brock and Rocco join forces to track them down. Meanwhile, the Doom Factory arches Rusty, unaware that they're on Blue Morpho's hit list.
Rusty throws a party for Christopher Lambert to celebrate the lunar eclipse, but things go horribly wrong. Meanwhile, Monarch sends Henchman 21 on a mission to convince the Guild that he's not Blue Morpho, while the Guild concludes that Rusty is the vigilante and takes appropriate measures.
Rusty takes a night after the OSI and the Guild join forces to set a trap at the penthouse for Blue Morpho. Meanwhile, Monarch meets his idol, Red Death... who is the bait in the OSI/Guild trap.