S3 E1 • Shadowman 9: In the Cradle of Destiny

The truths and half-truths about Dr. Venture's past arch nemesis, Dr. Girlfriend and The Monarch, are revealed.

S3 E2 • The Doctor is Sin

Dr. Venture learns that a life without an arch enemy is not fulfilling.

S3 E3 • The Invisible Hand of Fate

Billy Quizboy recovers the memories of his former life as a failed TV Quizboy, the loss of his hand and eye in a dogfight, his recruitment into the OSI, and his first mission as a spy.

S3 E4 • Home is Where the Hate Is

With the Monarch busy settling into his new home with his wife, a new villain arises to arch Dr. Venture.

S3 E5 • The Buddy System

Dr. Venture decides to raise money by running a Day Camp for Boy Adventurers. Things don't go quite as planned when a giant ape gets loose, Action Johnny loses it, Sgt. Hatred arrives for an unscheduled bush burning, Hank gets a new friend who pushes Brock's buttons, and the Monarch sends the Moppets in to spy.

S3 E6 • Dr. Quymn, Medicine Woman

Team Venture meets Team Quymn, led by Dr. Tara Quymn, Dr. Venture's childhood sweetheart. Her two twin daughters and manly bodyguard seem oddly familiar, but the two teams must join forces to battle a dreaded were-o-dile: half man, half crocodile.

S3 E7 • What Goes Down, Must Come Up

Brock and Dr. Venture stumble into a hidden state-of-the-art fallout shelter beneath the Venture compound, while Hank and Dean call in Dr. Orpheus to summon the Order of the Triad and help them out.

S3 E8 • Tears of a Sea Cow

The Monarch gets word that Dr. Venture and Brock are at a science conference, and decides to launch an attack on the Venture compound.

S3 E9 • Now Museum, Now You Don't

Dr. Jonas Venture Jr. builds a museum in honor of his "father," and invites all of Jonas Sr.'s old friends and enemies to the grand opening.

S3 E10 • The Lepidopterists

The Monarch leads an attack on his new arch-nemesis, Dr. Jonas Venture Jr., at his base on Spider Skull Island.

S3 E11 • ORB

Billy Quizboy has spent thirty years trying to decipher a series of cryptic clues hidden in Rusty Venture Cartoon Show episodes. Finally the solution to the mystery is at hand, but the answer forces Brock to discover what his true orders are.

S3 E12 • The Family That Slays Together, Stays Together (1)

The OSI has put a termination contract on Brock's head, and three top assassins plan to collect. Meanwhile, the Monarch and Sgt. Hatred battle to see who will be Dr. Venture's arch.

S3 E13 • The Family That Slays Together, Stays Together (2)

Continuing after the prior episode, General Traceter (alluded to in Season 1 during Brock's License exam in Mid-Life Chrysalis) heads a OSI assault team to go after Samson and the Venture Family after the original three assassins fail to do their job. Using ingenuity to save the Venture Family once more, Brock Samson hatched a plan to force OSI and Monarch's Henchmen to fight each other instead of pursuing the family. In the aftermath of the fight, OSI gains victory after one of Monarch's Flight Suits malfunctions and ends up shooting his own minions in friendly fire. After revealing himself being on neither side of the fight, Brock makes a shocking announcement to Thaddeus and General Traceter that would affect the rest of their lives.