This episode starts out at Zim's house, when a shadow falls over it. Zim is in his lab, reporting to the tallests. He's telling them that the humans are dumb, even though they are tall. Red asked how something that is tall can be dumb, and Zim is about to say something, when the doorbell rings. He tells the tallests to hold on, and goes and calls GIR. GIR is spit out through a tube thingy, and Zim tells him that he must behave like a human dog monster, and asked if he understood. GIR told him that he really didn't, and Zim told him to go answer the door.
Upstairs, GIR looks through the see hole of the door, and sees two aliens in masks standing there. GIR answers the door, and the alien, with really bad earth talk, pretty much tells him that they want to talk to Zim. GIR just looks at them, and they tell him that they aren't aliens, and start laughing, making slime come out of their ears.
Back in his lab, Zim is still talking to the tallests. Purple asks how tall they are, and Zim told them that they might be as tall as them. Red said that was fascinating, but the picture starts to wear away. Zim goes upstairs to see the aliens sitting on the couch, and GIR laying at one of their feet. Zim sees the badly disquise aliens, and they tell him that they are his new neighbors, and Zim tells them that they are wearing costumes. The aliens tell them that they aren't, and Zim told them that they were aliens, and their ship just interfeared with a very important call. One of the aliens said it was time for plan two, and the other one asked what plan two was. The other one said to stuff him in a sack, and Zim told GIR to go in defensive mode, and he jumped in the sack. They grabbed Zim and stuffed him in the sack, and they had a beam transport them to their ship. Up in the ship, the aliens took off their masks, and Zim cut himself out of the bag, asking who they were. Blue told him that he has fallen victim to their clever plan, calling him and earthling, and Zim told them that he threw him in a sack. Blue told him to be quiet, and that he's been chosen as the perfect test speciman for the human race, and told him to not attempt to risist them, and waved a little wand beam thingy that spelled obey. He told him that they have spent hundreds of Earth years wandering the galaxy adding to their collection, and it showed a whole bunch of empty glass things. Zim aksed where they were, Green told him that they escaped. Zim told them that he wasn't human, and took off his earth hair and eyes, saying that it was only a brillient disquise. Blue told him that he was human and they have proof, and turned on a TV which showed Zim in Skool saying, and Dib coming up to him saying that he know what he is, and Zim saying that he was human, human, human. Zim told them that he was lying, and asked if they heard of the mightu Irken race. Blue asked him how they explained the dog, and told him that humans keep dogs as pets. Zim told them that it was a disquise, and told GIR to cast off his mighty doggy rues, and GIR did a backflip and jumped out of the costume. Blue said that it was a smart dog, and told him to follow him, putting him in a glass case. Blue told him that he would make a fine part of their collection, and Zim asked if they could just drop him off. Zim told him that his house was right below them, he could just jump on the roof, and then he asked them if they were just hovering over an earth neighborhood in plain site. Blue told them that they were using advanced cloaking technologies, and their ship was disquised and perfectly unnoticable.
Outside, a giant whale was hovering above Zim's house. Back on the ship, Blue told Zim enough philosophy, and Zim told him that they weren't talking about philosophy, but was cut off when Blue said let the hideouse experements begin (in case you havn't noticed already, the names of the aliens are referred to by their eye color, just like the tallests). Green told him that they will begin by fusing him to another human being, and he pulled out a goafer. Zim told them what it was, but Blue told him to be quiet, and told Green to begin the fusion. Green took the goafer and put it on Zim's head, keeping it down with duct tape. Blue was drinking a juice and said that it was a success, and Green said yes, lets fuse him with his juice. Blue told him that they have already proven themselves in the fusion technology. Zim turned around to look for a way to escape, and finds an escape hole thingy. The two aliens are arguing, and Blue gets an idea, saying that they'll test how he reacts having things shoved through his head, but Green insists on fusing him with the juice. Zim tries to go through the hole, but it is no use. He takes the goafer off of his head, and throws it down the hole, telling him to go run for help.
Outside, a goafer falls from a floating whale. In the ship, the aliens are heading toward Zim. Zim points up, and they look up. They look down and he's gone, and look up again, and back down, and they keep doing this. They look behind them and Zim is running through some doorway. Blue asks Green if it is all his fault again abut the escape. Zim is running down a hallway, up a very tall ladder, that leads to a catwalk, and runs on it, leading to another catwalk, until he finds a door and goes in it, all the while, the aliens chasing him. It leads to a room that looks exactly like the one he just got done with, and hears a voice, calling him over to him.
The aliens are talking, and Blue said that they shouldn't have fused him, it made him twice as powerful, and twice as deadly.
Zim is walking among a row of glass cases, and finds a blob. Zim asked what he is, and he told him that he doesn't even know anymore, they fused him so many times. He tells him that eveyone else they kidnap escapes, but he's so heavy now and so disgusting. Zim asked how they got away, and he told him that the duct on the roof leads to the emergancy escape ships, if only he had an arm or a leg or someone to help him get there, and looks at Zim, but he is already gone. He starts crying, but Zim pressed something to make his capsule go somewhere else. Zim goes to where the aliens are talking, and Blue asks what if the juice had made him more powerful, and Green askes if they were talking about the same juice. Blue is sniffing himself, and then asks Green when was the last time he cleaned himself, and Green told him to define "self". Zim makes it to the escape pod room, and he calls GIR telling him to come to him. GIR pushes open the capsule and walks right past the aliens, into the pod. The capsule drops from the whale-ship right into Zim's yard. Zim and GIR get out of the capsule and walk back in their house.
Back in the ship, Blue is telling Green that he thought he told him to lock the escape pod room, and Green is saying just because he didn't lock it, it's his fault, and the escape pod room was unlocked, is that what he's trying to say, and Blue told him yes. Green said that if it makse him feel better to pretend he's stupid (and starts going duh and looking stupid), then he's going to fuse the other humans.
Back in Zim's lab, he's reporting to the tallests, saying that he may have found a species even dumber than the humans, and Purple asks if they were tall.
At Dib's house, Dib and Gaz are standing outside, when a giant floating baby comes flying in the air and takes away Dib.