This episode starts out with Zim and GIR falling the voot cruiser, yelling. GIR is eating a hot dog and Zim is pressing buttons, trying to land it safely. The launch pad for Zim's voot cruiser on his base opens up, and it lands, but not safeley. Zim orders the computer to the repair bay, and Zim is watching GIR drink his chocolate bubblegum. Zim tells him after he repairs the voot cruiser, he's going to run a test on his Artificial Intelligence chip, because it seems to be bad. Zim is about to say something else, when he sees a baby sitting in the window, watching everything that has just happened. Zim screams as the launch paf closes back up. The get into the house, and Zim tells GIR that the mission has been compromised, they have just been seen without their disquises. GIR tells Zim that Dib has seen them without their disquises, and he knows where they live, but Zim tells him that this is serious, and GIR screams shortly and goes to watch TV. Zim yells at him, and he screams shortly again and follows Zim.
Zim and GIR went to the launch pad, what would be the attic, and Zim made a window in the back. Zim saw the same baby, and said it was a spy, and they must inform the earth athorities. GIR said he was cute, and stinky looking, and Zim said he was a threat to the mission, but GIR replied that he was just a baby, and GIR yelled "HI BABY!". Zim ran after GIR and tackled him out of the window's site, and asked if he thought it wasn't a threat. GIR said yes, and Zim told him that's exactly what he wants him to think, and he must go and find out what it knows.
Zim goes to the baby's house and rings the doorbell, is a horrible disquise. He tells the woman that he is the neighborhood baby inspecter, and she asked inspector for what, and he yells at her that her resistance will be noted. He walks in and tells her that he's here to interigate him, and looks at the pictures, all of them looking the same, Noogums age 1-7. She tells him that he's upstairs, but Zim has already made it up there. He tells her to stay, due to the threat of contamination he must talk to Noogums alone. Zim walks into Noogums room and sees the baby playing with blocks. He tells him to cease the silent act, and asked what he was up too. The baby started to drool, and Zim told him to tell him everything he knows. Zim sniffed a couple of times, and started screaming about the stink, that it might be some kind of defence mechanism. Zim starts to go crazy, and runs.
Back at Zim's lab, Zim is working on something. Zim is saying that the infant is smarter than he thought, and that he'll need to use a higher percentage of brain skills to to out-wit him, stopping to gag in between words. GIR is in the background attached to a power amplifier, and Zim tells him that he was right about being harmless, and that he might have under-estimated him, amd over-estimated him. The stuff from the power amplifier gets near Zim, and Zim starts acting stupid. Zim yells at GIR to stop messing with it, and that he should worry less about what the baby can do, and more of what he can do, and that the power amplifier was sending out deadly rays of stupidness, when the doorbell rings. Zim gets worried and says the security system should have warned him if anyone set foot in the perimeter, and leaves to go answer it. GIR starts messing around with the power amplifier again once Zim is out of site.
Zim opens the door and finds no one is at it. Zim closes the door and tells the computer to run a diagnostic on the door-bell, but is cut off at bell when he turns around and sees a whole bunch of babys sitting in his living room. Zim tells the babys to get out of there, when one of the babys yells "Sieze the enemy!" and a whole bunch of babys start running for Zim and pile on him.
Zim is tied up to a chair, one of his disquise eyes off, and a baby pulling off the other one. Zim sees the leader baby, and says, "Noogums, I should have known." Noogums tells him not to call him that, that it is a disgrace to their race to be called Noogums. Zim asked what he should call him then, and he tells him to call him Shnooky. Zim tells him that he knew earth babys were from space, and Shnooky tells him that he was wrong. He says that his race didn't know they looked like human babys when they landed there seven years ago. He tells him the story of their first information gathering mission on earth. They were in a hospital, and one of the guys found the human baby maternity ward. They thought the earth military were keeping their people hostage, and the lights came on. Shnooky and another baby hid in the maternity laundry basket, while the others hailed the mothership, calling for an emergancy rescue, but gave the wrong coordanites. Their race was caught, but the babies that were rescued were still aboard the ship. They had no choice but to take the identity of the babies they captured on the ship, and that it has been seven years since that night. Zim asked what they wanted with him, and Shnooky demanded his ship. Zim says that they can't take his ship, and he said they'll tell the humans all about him if he doesn't. Zim called the computer and told it to take him to storage room 2. Shnooky told the babys to get him and to eat his feet off. Zim ran into an elevator and told the computer to take him down the the voot cruiser repair bay. The babys were on top of the elevator, and Zim told Shnooky that his ship is invader property, and that he won't get his filthy nub hands on it, and blasted a hole into one of the rooms, while the babys made it inside the elevator, but were lost going down. Zim took a tunnel to the repair bay, and GIR was beat-boxing into the power amplifier cords. (id you don't know what beat-boxing is, look at A Room With a Moose Episode Guide). Zim tells GIR that the babys are in the base and their after the voot cruiser, and that he needs to hold the babys off while he... but GIR yelled that he was going to play with the babys." Zim ignored him and pressed a button in the cruiser, but it said mal-function, and wrapped Zim up into something. The babys were almost knocking the door down, and Zim told GIR to do something. GIR turned on the power amplifier again, making that wave of stupidness thingy. Zim escaped from the cruiser, and turned off the power amplifier. The babys made it in, and told Zim that they were going to take his ship, and destroy his base, leaving him stranded there, just like them, and they were going to tell the humans all about him. Then Shnooky told them to form giganto baby, and all the babys made one giant baby. The baby started tearing apart Zim's base, and Zim used one of tubes that he was working on the cruiser with, and stuck it into the baby. The baby easily got it out, it smacked Zim out of the way, meanwhile, GIR is watching the whole thing eating a bucket of fried chicken. Zim is running from the baby, getting it tangeled up into wires, while he makes it to where GIR is sitting. He sees the amplifier, and hooks GIR up to it, turns it on, and sends out waves of stupidness. The giant baby breaks apart and all the babys are now originally babys, making them cry. Zim said it worked, and GIR was mad because he wanted to explode. Zim catapultes the babys back into their old homes thru their windows.