Buffy and her mother Joyce are at a mall discussing how inappropriate a dress is to wear. Joyce, realizing the stores are closing and she still has some necessary shopping to do, sends Buffy to pick up her dress while she runs some errands. On her way to the store, Buffy sees a guy wearing a cowboy hat romancing a girl. As she's going down the escalator, she looks in the mirror to see this guy has no reflection. She follows him upstairs, scares the girl off, and fights with him for a while. He runs away and she heads to her mom. As Buffy has forgotten to get the dress, her mom gives her a lecture on responsibility.
The next day, Cordelia and Xander are making out in a closet until Cordy mentions that she doesn't want anyone to know about their relationship. They reach for the doorknob, but stop and go back to making out. They fall to the floor and Xander reaches up to turn the light off. Later that day in health class, the teacher asks the students to list consequences of sex, and Xander and Cordy list each other's faults as consequences. Finally Willow gives the intended answer - pregnancy - and Mr. Whitmore says to learn about parenthood, the students will pair off to take care of an egg.
Xander and Willow enter the library with their eggs. Buffy, who had skipped health class, is handed an egg ("As a punishment, it's a little abstract...") that she will have to take care of as a single mother. Giles looks up the cowboys - the Gorch brothers - and suggests Buffy should hunt them with Angel's help. However, that night Buffy and Angel make out in the cemetery instead of hunting. The Gorch brothers watch from the cemetery wall, commenting that Buffy wasn't doing much slaying with Angel. That night, while Buffy is sleeping, her egg (dubbed "Eggbert" by Buffy) breaks open and an arm emerges and attaches itself to Buffy's face.
The next morning when she wakes up, the egg is back to normal. Back at the library, Giles finds Buffy, Willow, and Xander, who have been excused from class because their teacher did not show. Willow and Buffy are tired and sit down on the stairs. Xander begins to toss his egg nonchalantly in the air, as worried looks cross Buffy and Willow's faces. He hits the egg and it goes crashing to the ground, but doesn't break. He then reveals that he hard-boiled it. Giles suggests that Buffy should go back to hunting with Angel since last night was a bust. Buffy and Angel are yet again kissing instead of hunting in the cemetery. They stop to talk and the subject of children comes into play. Angel reveals how he can't have children. Buffy is shocked, but that doesn't change how she feels for him.
That night, Buffy sneaks back in through her window and sees her egg is moving. She gets closer and the creature inside leaps at her face. She pushes it onto the floor and it crawls under the bed. She uses an iron as a mirror to look around and sees nothing. It crawls on the floor some more. She grabs some scissors and stands waiting for it to show itself. It climbs up the wall behind her and she kills it with the scissors. Buffy calls Willow to warn her, but Willow's egg has already hatched. Buffy's mom then comes in and sees she is dressed. Buffy is grounded and sentenced to no after-school activities, and to only go to the library until her mother picks her up.
The next day at school, Willow tries to convince Buffy that her egg must have been a trap set by the cowboys. As they walk, the camera shows the little creature from the egg is hooked to Willow's spine. Xander, hungry, decides to eat his egg. He cracks it and when he is about to eat it, he screams when he sees the creature inside. In the science lab, the gang debates over dissecting the creatures. Willow volunteers and moments later, Cordelia's egg wakes up from inside her backpack. She suddenly picks up a rod and hits Buffy across the face with it. Willow grabs a microscope and hits Xander. They are thrown into a closet. Willow and the others are then seen grabbing hoes and pickaxes.
Mrs. Summers comes to school to pick up Buffy, but is instead turned into a host by Giles who puts a creature on her back. The two head down to the basement where they begin their work for the mother Bezoar. Buffy and Xander wake up and find two eggs by their side. Buffy smashes them and they head to the library in search of Giles. They find that Giles has been turned into a host for one of the creatures. Just as they begin to find information, Jonathan cries out in pain in the hall. They rush out only to find that he has been transformed. They follow and find everyone digging at and pulling eggs from the mother Bezoar. Xander pretends to be a host while Buffy fends off the Gorches. She hits them several times and then is thrown into the working pit.
Xander follows Cordelia and another guy. As they walk down a tunnel, he smashes the guy's head into the wall. Cordelia stops to swing at him and he ducks. She then hits him right on his bump. He screams in pain and then hits her across the face. The cowboys follow Buffy into the basement area and attract attention to them. Willow gives orders to have them killed. Everyone attacks them and Buffy and the cowboys manage to fight them off. The second cowboy comes out and is drawn to the mother creature. She grabs him and sucks him in. The first cowboy blames Buffy for what happened to his brother and throws her to the ground. She is sucked into the mother, but grabs a pickax on the way. She kills the mother Bezoar and with its control gone, all of the workers temporarily pass out.
Buffy comes up and out of the creature covered in black goo. She scares off the vampire. The next scene shows all the students leaving; Giles explains that it was a gas leak in the school basement. Buffy finds her mother, who is upset that Buffy had not studied in the library as she was instructed, and is confined to her room as punishment. Cut to Buffy and Angel kissing through Buffy's window as the camera pulls out.