When Dib finds out that Zim has no human organs, he attempts to exploit Zim’s ailment of head pigeons to get the skool’s nurse to examine Zim in hopes she will see the truth. However, when Dib blurts his plan out to Zim, Zim develops a device that will permit him to switch objects for organs, in which he begins to steal the organs of his fellow classmates in order to appear more human in time for his appointment at the nurse’s office.

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.

When it begins to rain one day, Zim becomes worried because he’s never experienced rain before. Dib takes notice of his fear and he coaxes Zim into stepping into the rain, only to discover that the Irken race has an innate weakness to water, which causes a burning sensation upon impact. Dib decides to exploit this new fact to create the ultimate weapon to stop Zim once and for all, but Zim himself attempts to find a way to protect himself from this new found weakness, which all leads up to a confrontation that neither of them would have expected.

When Dib finally manages to be permitted to present his findings on Zim to the Swollen Eyeball Network, he believes he will be able to put an end to Zim’s schemes once and for all. However, when he discovers that he needs his father’s permission and since his father is busy working on his television show, Dib must venture into the studio where his father is in order to attempt to get the signature he needs; though he soon discovers that speaking to his father isn’t going to be as easy as it should be.

While at skool one day, Ms. Bitters tells the class that they need a new pet hamster due to the orders of the skool’s board of directors. When the hamster arrives, all the children love the hamster because of how adorable it is, in which Zim decides to exploit that fact since the hamster could help make the humans too weak to resist him. Zim plants an Irken device on the hamster that will permit it to grow larger and be controlled by Zim, but when the hamster grows rampant and breaks free, Zim must attempt to stop the huge hamster from destroying his headquarters, all the while worrying about the growing military presence that may have no choice but to attack the hamster, which would ruin all of his efforts.

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.

When Gaz sees an advertisement for the new handheld gaming console, the Game Slave 2, she decides that she really needs to go to the mall in order to get one. However, when her father insists that she takes Dib to the mall as well, he forces her to wait until Mysterious Mysteries goes off, which causes them to arrive at the mall late. Gaz, in rage, tricks Dib into running off into the underground parking lot while she attempts to get a Game Slave 2; though Gaz discovers an annoying kid managed to get the last copy so she seeks to steal his copy, all the while Dib must attempt to get out of the underground parking lot, which is filled with rat-like people who just annoy him.

The skool is holding a candy drive in order to get some finances, in which the individual who sells the most chocolate bars will get a secret mystery prize. Zim becomes interested and he attempts to find a way to sell the most chocolate bars, which causes Dib to get into the contest in order to gain a defeat over Zim. Zim soon realizes, however, that he may have to take drastic measures in order to sell more candy bars than Dib.

When Professor Membrane invites some of his colleagues over to the house, they insult and mock Dib because of his hobby of paranormal investigation. Matters become even worse for Dib when Mysterious Mysteries begins to show a segment on Chickenfoot, a being that is obviously a guy in a suit. Dib decides to go on a crusade to prove Chickenfoot is a fraud in order to establish the fact that paranormal investigation also disproves the frauds along with proving the real mysteries, though will Dib be able to find the elusive Chickenfoot and even if he does, how will he manage to get the suit off of him?

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.

An Irken masquerades as the new girl at school in order to settle an old score with Zim.

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.

While at school one day, Zim throws another fit about the lunch food so Dib throws a muffin at him, which causes Zim to run away in anger. The next day, a pair of Meekrob come to Dib in his sleep and grant him marvelous super powers, in which Dib decides to use to put an end to Zim once and for all. When Dib manages to suppress Zim quite easily, he decides to use his power for the greater good and he lives out the wonderful life he always wanted to have; though perhaps it’s too wonderful.

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.

During Probing Day, the day where the Tallest evaluate the Invaders’ performances, Zim has Dib captured in a space-time-field prison which is keeping him in slow motion, in which Zim wants to perform experiments on him for the Tallest. However, when a malfunction causes the prison to explode, Zim finds a piece of explosion that is expanding very slowly; in which Zim believes he can end if he throws it into the city’s cesspool. However, when he discovers that getting the explosion to the cesspool is much more difficult than he expected, he finds that he may just have to use unconventional means to complete the task.

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.

Dib summons Mortos der Soulstealer, a mystical being who emerges once every thousand years, in order to wish for him to steal ZIM’s soul. However, when it turns out that Mortos needs to recharge his power before he can complete the task that Dib requested, Dib must help him do many absurd things in hopes of putting an end to ZIM once and for all. Meanwhile, ZIM heads around town undergoing his latest evil scheme, which is the reason Dib was so eager to enlist Mortos’ help in the first place.

When Dib finally manages to get a spy camera inside Zim’s house, he plans to exploit the moment to show the Swollen Eyeball Network the truth about Zim’s nature. Unfortunately for Dib, Zim is more concerned with Gir’s waffles than his next evil plan, which causes Dib some complications as there is nothing special about waffles. However, when something out of the ordinary does occur, Dib believes he may just have a chance to succeed in his plans.

When Dib discovers that Tak’s ship he recovered has a built in AI, he decides to reprogram the ship with his own personality. While Dib is quite pleased with initial results, the spaceship begins to behave more and more like the real Dib and it attempts to actually take his place. All of the attention of a huge spaceship going to school causes Zim to realize that it’s really Tak’s ship, so he plans to override the machines AI and order it to attack Dib; though can he really force a machine so smart to attack it’s counterpart?

Class elections find Zim running against a Dib-backed Willy for president.