While the boys are waiting for the school bus, Eric Cartman explains the odd nightmare he had the previous night involving alien visitors abducting him and probing him when he went to bed. Cartman's friends, Kyle Broflovski and Stan Marsh, try to convince him that his dream was a reality. Meanwhile, aliens abduct Ike Broflovski.
At the beginning of the episode, Cartman details his dream of him being abducted by aliens and receiving an anal probe. The others try to convince him it was real, but Cartman assumes they are just trying to scare him. Chef then pulls up and asks the boys if they saw a visitor spaceship, inadvertently confirming the reality behind Cartman's "dream". Chef is also wearing a T-shirt with a picture of an alien "visitor" on the back with the word "Believe", scaring Cartman even more. As Chef leaves, the school bus arrives, introducing Ms. Crabtree, a scary-looking, loudmouthed, middle-aged school bus driver who constantly tells the children to "Sit down and shut up!" As the bus is driving away, Kyle looks back and sees his brother Ike, being held by two visitors.
Meanwhile, Officer Barbrady investigates another cow mutilation on Farmer Carl Denkins' farm. Several other visitors try to lure away cows by whistling and offering straw. The cows are not falling into the trap as several aliens have turned them inside out. Barbrady explains that a cow turning inside out is nothing unusual, clearly revealing that he is an incompetent law officer. Also, when helicopters fly by, and the farmer asks what they were, Barbrady says they were pigeons.
The boys are now at school. Worried about his brother and how his parents will react, Kyle asks Mr. Garrison if he can be excused from school to find his brother. Mr. Garrison tells Kyle he has to ask his hand puppet, Mr. Hat, this is when Mr. Garrison and Mr. Hat's shared catchphrase of, "You go to hell! You go to hell and you die!" is introduced. Cartman laughs at Kyle and ends up farting fire at one of the children, Pip Pirrip.
After being told visitors abducted Kyle's brother, Chef freaks out and says, "What the hell do you think you are doing in school eating Salisbury steak? Go find him, dammit!" A cyclops-like robot then pops up from behind Cartman and quickly retreats from whence it came, this ends up being the anal probe from Cartman's "dream". To help the children find Kyle's brother, Chef pulls the fire alarm.
When the children get out of school, Cartman still doesn't believe that he has gotten an anal probe from the visitors. While insisting that he not be under mind control, a beam from above hits him out of nowhere as he suddenly sings "I Love to Singa". The children use this as proof that visitors are controlling Cartman. Cartman, in all ignorance, still disagrees with their idea.
Just then, a spaceship appears. Kyle demands that they return Ike. In response, the aliens blast Kenny with a star-shaped object. Which causes Kenny to fly into the street, and he appears to be dead. Stan and Kyle respond by saying, "Oh my God! They killed Kenny!" "You bastards!" for the first time. Kenny, however, isn't dead yet. He stands up, only to have the herd of cattle that ran away from Jenkins' farm trample him. Kenny is still alive after this. Officer Barbrady finally kills him, in pursuit of the cattle, by running him over in his police car. Despite this, Cartman still denies that the visitors are real and that Kenny is dead. He decides to go home.
Stan and Kyle go to Stark's Pond to meet Wendy, although Kyle wants to keep looking for Ike. Wendy shows up, and Stan vomits when she speaks to him. Kyle tells Wendy what happened to his brother, and she suggests that they use Cartman as bait to draw the aliens back.
To lure the visitors back, Stan, Kyle, and Wendy tie Cartman up to a tree. After Cartman farts flames several times, an 80-feet wide satellite dish protrudes from his rectum. After the visitor spaceships show up, Ike is revealed when a door on the ship opens. Kyle gets Ike to jump from the ship by telling him to do his impersonation of David Caruso's career. Before boarding their spaceship, the visitors talk to the cows. The visitors tell the cows that they are the most intelligent life form that they found on Planet Earth. The cows want to know why they turned some of their cow friends inside, tells him to do his impersonation of David Caruso's career. Before boarding their spaceship, the visitors talk to the cows. The visitors tell the cows that they are the most intelligent life form that they found on Planet Earth. The cows want to know why they turned some of their cow friends inside out; the visitors explain that it was "Carl's fault, he's new" and give them a device that makes people sing. Before leaving, the visitors abduct Cartman again.
Meanwhile, Officer Barbrady find the cows and demands them to come back, but the cows use the device the visitors made on him and make him sing I Love To Singa.
The next morning, Cartman falls from the sky and lands at the bus stop. One of his eyes is red. He immediately describes to Stan and Kyle a "dream" he had about getting pinkeye from Scott Baio aboard the alien spacecraft.