The episode begins in the middle of one of the Brain's plots to take over the world. It's Halloween, and he's invented a device which allows him to transmit via Jack O'Lantern and control the minds of children. The trick-or-treating scene is pretty nifty, what with the costumes and all:
Of course, the plan fails, and the Brain laments that he's tried everything short of selling his soul to take over the world. Usually, this would elicit no response, but since it's a Halloween episode there's a glowing red breeze and a man calling himself Mister Itch appears. The man knows an awful lot about the Brain, including the fact that he once decided to chuck it all in favor of a failed rhythmic gymnastics career, and wants to help him take over the world. In order to prove his sincerity, Itch gives Pinky a trial wish. Pinky wishes for a radish rose whatchamwhozits, and Itch complies by turning the Brain into a melon ball thingamabob. The Brain seems convinced, but changes his mind and storms back to the lab. Itch thinks there may be another way...
Later, Pinky returns to the lab as well, and wonders if Itch could really do all the things he promised. The Brain sarcastically replies that yes, Itch probably could, but the Brain can just wave a magic pencil and suddenly the world will be his.
To his surprise, he waves a magic pencil and suddenly the world is his.
As it turns out, this is not because of a magic pencil, but rather because Pinky sold his soul. To the Devil. At this point, I think I should tell you that the spin-off aired in prime time. I doubt they could get away with Pinky selling his soul to the Devil on Saturday mornings, at least not as overtly as this. Mister Itch takes Pinky away to Hades, and while Brain seems initially upset that Pinky is gone, he thinks his newfound status will get him through it. Why shouldn't it? He has everything he ever wanted: the affection of the world's population, supreme control, and his nemesis Snowball acting as his jester.
Not all is well, however, as the Brain continues to miss Pinky, trying to mask this feeling by claiming he just wants to know where Pinky kept the food pellets. Snowball suggests he go to Hades, and gives the Brain a map which guides him through the Department of Motor Vehicles and into the Underworld. Brain makes it into Hades after masquerading as a fatally malnourished Rush Limbaugh, and after exclaiming “YES!” at the gates, wonders why he's celebrating since he's now in Hell.
Pinky, meanwhile, is enjoying all the tortures Mister Itch can throw at him. He claims that the only real torture is being separated from his best friend, and who should choose that moment to show up but the Brain? He demands Pinky leave Hades with him, citing his need for food pellets, but Itch won't let Pinky go without a fight. The Brain challenges him to rhythmic gymnastics, and Itch calmly insinuates that he invented that “infernal sport”. What's more is that, if the Brain wins, he'll get Pinky but lose the world and forfeit any future attempts to take it over. The Brain still accepts the challenge.
While the Brain does well, earning a perfect ten, Itch gets an eleven, claiming that while he promised the Brain a challenge, he never promised that it would be a fair one. Pinky and the Brain have a tearful good-bye, but Pinky take solace in the fact that he'll get the radish rose whatchamwhozits promised to him by Itch. As it turns out, Itch doesn't know what a radish rose whatchamwhozits is, and so the contract for Pinky's soul is null and void. Itch takes affront at this, turns into a more traditional demonic Devil, and chases Pinky and the Brain out of Hades. They manage to escape back to the lab, where Snowball is displeased, having also made a pact with Itch. With that, the Brain vows to try to take over the world again the following night, and all is right with the world.
With this synopsis, I've managed to completely eradicate most of the actual humor from the episode. That's the problem with reviewing something that's actually good: you can't make snarky comments along the way. Well, you can, but it's futile. This was an exceptional episode of the show, and a pretty good Halloween special to boot. Really, though, with a cartoon about a lab mouse who sells his soul so his friend can rule the world, it either has to turn out really well or really terrible. I'm happy to say it's the former. If you'd like to see the actual episode, it's on DVD, the link which follows. I suppose you could also find it through other, nefarious means as well. Just don't sell your soul.