After another day at the Earth skool, Ms. Bitters reminds the children that it’s Parent Teacher Night and that all the parents must come to the skool at the end of the day. Zim becomes worried because his robotic parents aren’t programmed for such a task yet and he cannot permit them to blow his cover, so he attempts to help them become the parents they should be, but Gir’s carefree nature soon puts his plans in jeopardy.

When Zim makes a huge scene over his inability to eat lunch food, he overhears one of the girls at school talking about how inhuman he seems to be and how he has no friends. In an attempt to appear more normal, Zim decides to spend time with a student named Keef, though Zim soon finishes his plan and he considers himself normal, so he tries to get Keef to leave him alone. Much to Zim’s chagrin, however, Keef continues to follow Zim around, so Zim decides to take unorthodox measures to ensure Keef leaves him alone.

After Zim watches an old movie where some invading aliens are defeated by some bacteria, he begins to study germs more. However, when he discovers that such germs truthfully are everywhere, he begins a crusade to kill every germ in his headquarters so that he can be safe, which is helped by the fact that Gir had some cleaning spray handy in the house; though when the cleaning bottle runes dry, Zim must attempt to go to the store and get some more, despite the fact that he knows just how many germs are out there.

Zim attempts to test some of the defenses that Earth has by taking his Voot out for a drive to monitor local police units. However, when a bumble bee crashes into his vehicle, Zim comes crashing down in the park, in which he heads home because he will be unable to recover it the next day. However, when a space cult known as the Saucer Morons discover the Voot first, Zim must find a way to get his vehicle back without causing him to lose his cover.

Ms. Bitters is assigning students their mentors for Career Day through the use of an aptitude test and a machine. Both Dim and Zim attempt to get their desired professions on the test, in which Dib manages to get paired with a Paranormal Investigator while Zim gets stuck working at a fast food facility. However, when Zim misinterprets the 8 billion served sign and thinks that the individuals in charge of the company are the leaders of the planet, he becomes dedicated to his job in hopes of being promoted to Lord of All Humans. However, thanks to the alignment of the planets, Zim is about to go through some uncontrollable changes that could jeopardize his mission; which Dib is looking to exploit, though both Zim and Dib find their situations to go much different than they anticipated.

When Zim formulates a plan to get revenge on his skoolmates and especially Dib, he gets them all participating on a fieldtrip. Dib, however, realizes that the driver of the bus isn’t real, but due to his constant theories, the other students disregard his warnings. Zim decides to gloat about his magnificent plan and he informs Dib of every detail in confidence that Dib can do nothing to stop him, though Dib refuses to give up and he does everything he can to save his skoolmates and himself; despite the fact that he doesn’t know why Zim’s plans involve a room with a moose.

Zim finally finishes one of his self proclaimed brilliant inventions, a space-time-object-transfer device, in which he plans to send a giant robot into the past in order to put an end to Dib once and for all. However, when the robot isn’t compatible with the temporal field, he throws a rubber pig into the vortex instead, which turns out to be compatible and it causes Dib to crash his tricycle in the past. Zim decides to send many more rubber pigs into Dib’s past, which ultimately affect him in the future; though when Zim overdoes himself, he discovers that history isn’t something that should be messed with.

Dib believes he has figured out a way to successfully tunnel into Zim’s underground base, but when his father comes in and announces that it’s the Membrane family’s night out and that Gaz gets to pick the place to eat, Dib runs off saying that he will be back in time for them to leave. However, when Dib fails to arrive on time, Professor Membrane decides to wait until Dib gets back, which causes Gaz to become quite frustrated as she really wanted to get some of her favorite food; she decides to go find Dib at Zim’s place and despite the fact that Zim’s already taken Dib into an in-space laboratory, she refuses to miss her opportunity to eat out so she plans to let nothing get in her way.

When Dib once again notices that Zim isn’t eating his food, he throws a piece of bologna at him in order to taunt him, in which the bologna fuses with Zim’s skin, causing him immense pain. Zim vows to get his revenge and during the next day of school, Dib sits on a tack, which causes Zim to begin laughing hysterically. Dib believes Zim is just being pathetic, but when Dib begins to transform into a living piece of bologna, he realizes that Zim’s plan was better than he had thought and he must formulate a method of curing himself before it’s too late.

When Zim goes to Mars to attempt to find a way to destroy the Earth, figuring that whatever killed the life on Mars may work for Earth as well, he stumbles across the face on Mars, which he later discovers that is actually the controls for a spaceship, in which the entire planet of Mars was the spaceship. Dib learns of this and he attempts to go to NASAPLACE in order to get them to see what Zim is doing, but they refuse to believe him as they can’t look at the monitors. Will Dib be able to find a way to stop Zim before he uses the red planet to squish all the life out of the Earth?

The Almighty tallest are examining a storage planet in order to send valuable goods to the Invaders to help them on their missions. They decide to send a Megadoomer Combat Stealth Mech to Invader Tenn to help her conquest of the planet Meekrob and they decide to send a box of malfunctioning SIR units to Invader ZIM, but when the two packages addresses are switched by an angry slave, ZIM gets the Megadoomer and plans to use his new gift from the Tallest to put an end to Dib once and for all.

When Zim attempts to taint the Earth’s cow-meat supply with sewer water is ruined because of Gir’s antics, he decides to increase the power on Gir’s behavioral modifier, which will permit him to stay in serious mode all the time. However, when the serious Gir starts to consider Zim a threat to the mission and runs off to learn things on his own accord, it’s up to Zim and Squidman to find Gir and turn down the power on his behavioral modifier before too many individuals see them and jeopardize their mission.

When Zim’s constant requests to the Tallest get on their nerves, they attempt to remind him that he is an Invader, not a battle soldier, and that he doesn’t have the training to use the equipment he requested. In order for Zim to prove himself to them, they send him to Hobo 13, an elite training facility that only the best of soldiers stand a chance of completing. While the Tallest hope that Zim will die on the mission and be gone once and for all, they soon discover that Zim is much more cunning than they gave him credit for.

Zim's Yuletide plan to overtake Earth by posing as Santa starts to backfire when he takes on characteristics of the Jolly Old Elf. Dib, meanwhile, tries to save the population from impending doom.

Gaz develops an unhealthy fondness for the flavor of pork.

Zim's former boss is mad at him for leaving, so he kidnaps him and makes him work at his old job on the planet Foodcourtia.