|The Venture Bros. episode|
|What Goes Down Must Come Up|
|Orig. Airdate||July 13, 2008|
Brock and Dr. Venture, while attempting to re-use some old machinery, both wind up trapped underground. While Hank and Dean reach out for help to find their missing father and bodyguard, Brock meets a former colleague of Dr. Jonas Venture Sr. and Dr. Venture meets a group of crazed fanatics living in his basement.
Dr. Venture and Brock Samson are attempting to use some old digging machinery for an unknown project when suddenly Dr. Venture falls through a shaft in the floor and Brock accidentally wrecks the digging machine into the hole, trapping Dr. Venture. Brock immediately tries to contact Doc via their wrist watches, but to no avail. He then proceeds to search a nearby room where Dr. Paul Entmann has been trapped for the past 30 years. Brock and Entmann quickly discover that they're now both trapped in a room (which opens only from the outside) for 40 years. Meanwhile, Dr. Venture begins to investigate the series of tunnels beneath his home whereupon he meets The Fire Starter, who is frantically running around and proclaiming that he's the fire starter.compound's basement. The team then joins together to find the whereabouts of the missing Dr. Venture and Brock, only to discover a more, sinister being is present. This makes the Triad flee in fear, and even makes Jefferson Twilight soil himself.
Dr. Orpheus, concerned about this frightening entity, seeks the wisdom of his master, while Jefferson and Dean grab and extra pair of Spider-man pants and Aqua-man underwear.
While Orpheus is being consulted by his master, Dr. Venture stumbles upon a phone which links him to Brock and Dr. Entman, he calls Brock and requests assistance, which, of course, cannot be given since Brock is also trapped somewhere. Dr. Venture is cut off when The Fire Starter's friends arrive and haul him off back to their base.
Back above ground, Pete White has been recruited to help find Brock and the Doc, and he quickly sets himself up in the security room and begins to check all of the surveillance videos until he spots Brock walking into a room downstairs. He tries to access the camera for said room, but he is unable to do so, and asks the boys to hook any cables up that may have been unplugged under the table. The boys hook the one undone cable up, which activates M.U.T.H.E.R., a super-computer that was built to run the nuclear fallout zone that Dr. Venture accidentally fell into. M.U.T.H.E.R. then demands Dr. Jonas Venture Sr.'s presence, and after a few seconds she threatens to launch a nuclear missile if she does not see him.
Meanwhile, back in the fallout zone, Dr. Venture is brought before a group of people, who either resemble various musicians or have on Rusty Boy Adventurer shirts on, and they decide what is to become of Dr. Venture, an "outsider." They consult an old video of Dr. Jonas Venture Sr. that was intended for Rusty to use in the event of a nuclear fallout. When Dr. Jonas Venture Sr. speaks to Rusty, the fanatics believe that he is their "father" and that they are all named "Rusty." The video covers basic personal hygiene , and Dr. Venture quickly ends the video and demands that he be taken back to the surface.
The Order of the Triad, tired of waiting around for something to happen, goes out to locate Dr. Venture and Brock, while Entmann tells Brock all about the nuclear fallout zone. Saying that Dr. Jonas Venture Sr. built M.U.T.H.E.R. to help assist the supposedly distraught survivors of a nuclear bombing and M.U.T.H.E.R. was supposed to pump in small amounts of "mood-enhancing drugs" into the vents, but instead M.U.T.H.E.R. pumped huge amounts of the gas into the chambers when the original Team Venture was giving some orphans a tour of the area. Dr. Jonas Venture Sr. came to rescue only his comrades, Colonel Gentleman, Kano, and The Action Man, leaving the children trapped underground.
Back above the ground, the Triad has decided to take the digging machine that Brock was using earlier to go rescue him and Dr. Venture. Jefferson starts the machine up, much to the surprise of Dr. Orpheus, and they make their way down to quickly rescue Brock and Entmann. Meanwhile, Dr. Venture is being chased by the crazed Venture fanatics and he runs into a dead end in the missile silo, which houses the nuclear missile that's about to launch in a matter of seconds.
As the missile lifts Rusty out of the tunnels and back above ground, he naturally begins to panic, unlike his friends and family who are sitting back and enjoying the show from the safety of his compound. Lucky for Dr. Venture, the missile falls over, but it spills out a large amount of feces.
The final scene shows Dr. Venture sealing up the shaft he fell into earlier while talking to Pete White about how the orphans kept their waste in the missile so that when it would launch it would "make them clean again." Meanwhile, Brock and Entmann have set M.U.T.H.E.R. up with the video reel of Dr. Jonas Venture Sr.
 Fun Facts
- Dr. Venture mentioned that the orphans were somehow able to get VH1 Classic, which would explain why some of them dressed up. Appearances include:
- Trevor Horn from the Buggles
- Michael Jackson in Thriller
- Keith Flint (vocalist and guitarist for the Prodigy) in Firestarter
- David Bowie in Ashes to Ashes
- The 3 men and little girl are from Art of Noise's Close (To The Edit) video. The audio when they first appear is a nod to the song.
- The lead military-garbed orphan looks and sounds just like General Boy, a character that appeared in several Devo music videos. Later on, Devo mascot Booji Boy also appears as a face in the crowd.
- In the control/surveillance room, when Pete White is telling the boys he and Rusty flip on the night vision when Brock has a lady friend over, he abruptly stops and pushes a box of tissue to the left of the control panels. In the next shot, when the boys go under the control panel to check for loose wires, the box of tissues is gone.
- M.U.T.H.E.R. is likely a reference to the supercomputer MU-TH-R from the movie Alien.
- The drug hallucinations reference the films "Jacob's Ladder" (the shaking heads) and "The Shining" (Col. Gentleman/man in costume scene).
- Jefferson Twilight raising pigeons on the roof is likely a reference to Forrest Whittaker's character "Ghost Dog".
- The underground bunker with the ICBM might be a reference to Beneath The Planet Of The Apes, the second movie in the series in which mutated humans worship a missile armed with a cobalt bomb.
- When Al and Jefferson Twilight are handed the dolls, Jefferson exclaims "Finally! Merchandising - that's where the real money's at!", which is a reference to Spaceballs.
 Voice Cast