Buffy runs into a cowboy vampire at the mall, then returns to her mom Joyce, who is becoming increasingly annoyed about her daughter's lack of responsibility. The next day at school in health class, the students are asked to take care of an egg as if it were a baby, to teach them how much responsibility it takes to be a parent. Giles warns Buffy about the vamp she ran into -- he and his brother, the Gorches, are cowboy vampires, but he's not sure why they've been drawn to Sunnydale at this time. But Buffy's head is not into slaying or egg-raising these days -- she's ever more into the dreamy Angel, and her nights at the cemetery have become nothing more than make-out sessions with her undead man. When Buffy returns from her non-productive investigation of the Gorches, she finds her egg baby shaking -- she's wigged. A gross scorpion-like slimy creature bursts from it and attacks her, but she manages to stab it to death. She calls Willow to let her know what's happened, but Willow says her own egg baby is fine, and there's nothing to worry about. But we see that Willow is lying, because her own egg is indeed broken apart, and she has a spaced-out look on her face. When Joyce enters Buffy's room and finds her fully dressed, she thinks she's getting ready to sneak out and grounds her.

The next day at school, Willow gathers the gang for a monster autopsy. But she and Cordelia, whose egg has also spawned a creature, wind up decking Buffy and Xander and dragging them into a broom closet. Then, Willow, Cordy and a bunch of other students and teachers head zombie-like to the basement with shovels and axes. Even Joyce winds up getting possessed, when she comes to school to fetch her grounded daughter and instead finds a spaced-out Giles, who throws one of the creatures onto her.

When Buffy and Xander come to, they find a book which explains what's going on. There is a creature in the basement called a bazor, whose offspring attach themselves to human hosts and take control of their motor functions. They follow a possessed student to the basement and discover Willow, Cordy, Giles, Joyce, and a bunch of others harvesting eggs from a gigantic slimy parasite. As Buffy looks for a weapon big enough to toast this mama bazor, the Gorch brothers show up. One of the bazor's tentacles drags Buffy under the floor, and suddenly all the babies fall off of their human hosts, who then fall to the ground. Somehow Buffy emerges victorious and the Gorches know they've met their match. The newly-unzombied Giles stumbles for an explanation for what's happened to everyone, and tells the student body there'd been a gas leak. Once Joyce gets her bearing, Buffy is more grounded than ever. She's not allowed to leave her room, but that doesn't stop her from making out with Angel, who she kisses from her window as he is perched outside.