Numbuh 5 and her family have just finished eating dinner. Her father comments that it's nice to see Numbuh 5 and Cree being friendly again. They seem to be getting along... until it's discovered they're pointing ray guns at each other underneath the table.
Then Numbuh 5's father suggests that they get chocolate and marshmallows. Both Numbuh 5 and Cree say they'll get it, but Numbuh 5 said it first and leaves, narrowly avoiding a blast from Cree's ray gun, which, of course, their parents are oblivious to. Numbuh 5 goes into the garage and opens the "refrigerator", which turns out to be a rocket in disguise. She flies out to Mars, where there are these large marshmallows. She blasts them and they turn into a bunch of really small marshmallows, then she takes some of them and goes back into the rocket. She says that although it's a bit more work, marshmallows always taste better fresh.
Then the rocket goes back to her house, but she finds that her parents and Cree are all covered in hardened chocolate (or have they been turned to chocolate and are standing still?). Then Numbuh 5 discovers the words, "I haff returned", written in chocolate on the wall. She takes the moment to run over to the treehouse, which is where a chocolate trail leads. The rest of the KND meanwhile are fighting something that's spewing out chocolate at them (it's unknown who or what it is yet), but it blasts them and they're turned to chocolate/frozen in chocolate. The culprit is a giant, chocolate version of Heinrich Von Marzipan. Chocolate spreads across the floor wherever he walks. Numbuh 5 bursts in and confronts Heinrich.
Now it's revealed what happened: after he was knocked into a chocolate volcano by Numbuh 5 (in Op: RABBIT), Heinrich fell into the choco-lava and fused with it. Now that giant chocolate monster everyone saw, everything he touches turns to chocolate. Although happy at first, he later got a powerful desire for a cheeseburger. But when he tried to eat it, it turned into chocolate, as did everything else he tried to eat. Numbuh 5 suggests turning himself into the Kids Next Door, as maybe their scientists could cure them. Heinrich, however, says that's not her concern, and that she should be more worried about spending her life chocolatized. He tries to bombard her with chocolate, and she shoots a marshmallow out of her gun, which stops it. Apparently marshmallows make chocolate more messy or something. But he warns Numbuh 5 that she only has a few marshmallows left, while he's got unlimited chocolate. Numbuh 5 takes the moment to escape, and uses rocket jets to fly off, but Heinrich (who can apparently make chocolate bridges to run across) pursues her and turns the rocket jets to chocolate, causing her to fall. Numbuh 5, of course, lands in a tree and then resumes her running. She quickly goes into the rocket in her house and takes off, just before it turns to chocolate. But Heinrich managed to stay with her and enters the rocket. Numbuh 5 turns the rocket upward so he falls to the back, but Heinrich jumps up to her and grabs her leg. Now Numbuh 5 is slowly turning to chocolate (or is it being covered in chocolate?). However, it turns out that she was deliberately heading towards the sun, so Heinrich melts into liquid chocolate. Numbuh 5 manages to break off the chocolate on her (turns out they're chocolate-covered and not turned to chocolate), and pulls a lever, causing marshmallows to fall onto Heinrich, which keeps him that way. After that, Numbuh 5 put in a call to Kids Next Door Global Command, who rescued the rest of the KND and her parents from the chocolate, though Cree had "mysteriously" disappeared. Heinrich's melted body was transported to the KND Arctic Base, where the scientists managed to turn him back to normal (a reference to the bacta tank in Star Wars Episode V: The Empire Strikes Back) though they then put him in the prison, where numerous other KND villains were imprisoned, as well. Later, Numbuh 5 visits him. Heinrich is convinced she's just there to gloat, but she just gives him a bag and leaves. He opens it and finds... a cheeseburger. He eagerly starts eating it... until he finds there's a pickle in it, and he hates pickles.
The episode begins with someone dressed as a matador walking towards a door. The light shining behind the figure obscures it. When the figure passes through the door, it is revealed as Numbuh Four. The audience cheers for him, but they throw lollipops instead of the traditional flowers. Numbuh 4 then turns to face his opponent: a fat businessman who is snarling and acting very much like a bull. The next few scenes consist of Numbuh 4 fighting and humiliating the adult in several comical situations.
Numbuh 4 sits in an office while he is handed Yipper cards by Ernest, the bully who runs the fights (called the Bully Fights). Numbuh 4 calls him "Ernie", getting him mad, and he corrects Numbuh 4 on his name; Ernie also tells Numbuh 4 not to forget about the match that night. We then see Numbuh 4 riding the elevator up to the treehouse, where he is confronted by Numbuhs 1, 2, 3, and 5, who are angry at him deserting the team to torture adults. Numbuh Two reminds Numbuh Four that the adults they fight are evil, and they don't get the adults hyped up on coffee like the Bullies do (this, then, is the source of the adults' madness). Numbuh 1 also reminds Numbuh 4 of the team's upcoming night battle against the "insidious" Soccer Mom. The team heads for the S.C.A.M.P.E.R., leaving Numbuh 4 to groan about this choice he's forced to make: the mission or the match.
At the Bully Fights, Ernie says that Numbuh 4 had better show, just as the S.C.A.M.P.E.R. flies overhead. The team near the soccer field where Soccer Mom is, but are pelted by soccer balls in short order. Numbuh 1 orders evasive maneuvers, and when Numbuh 4's chair spins around, we see he has been replaced by a dummy. The real Numbuh Four arrives at the Bully Fights and told by Ernie to "get out there" before "they [the audience] have a riot out there". Numbuh 4 enters the ring only to find he's about to fight his dad! Numbuh 4 slaps his dad out of the coffee-induced trance, and the two of them run from the Bullies, who are angry that Numbuh 4 let them down.
In a room full of cages, Numbuh 4's dad laments the fate of the adults-- they all signed up for a "How to be a Better Dad" seminar, but it was all along a trap-- the Bullies pumped the adults full of coffee, until they were all confused, angry, crazy and ready to charge at anything or anyone, even their own kids! As Ernie and his pals bust in, Numbuh 4 says he has a plan. Ernie and the Bullies charge into the room, but are chased out by Numbuh 4 and his dad riding on the coffee-crazed adults. Meanwhile, at the soccer field, while Numbuh 2, 3 and 5 are tied to the net and Numbuh 1, who is the soccer ball, trapped in the dirt and wearing a soccer ball-like mask, Soccer Mom is shouting at the crying fourth-graders for not playing, then she says they can "play with their stupid Rainbow Monkeys" while she prepares to kick Numbuh 1. She is about to knock his lights about, but Numbuh 4 and Mr. Beetles arrive with the adult stampede and bowl her over.
A properly trussed-up Soccer Mom is being led to a rocket that will take her to KND Arctic Prison, the coffee-crazed adults are back to normal and Numbuh 4 apologizes to the team for his mistake. He then says that saving the adults and his team makes up for it, and Numbuh 5 gives him a friendly noogie in return. Numbuh 4 then looks off to the side and notices that "someone left a soccer ball" (the still-trapped Numbuh 1) and the scene fades while Nigel screams in pain.