The class is on a field trip to the zoo. A group of delinquents tease Buffy about not having friends.
The four delinquents pick on a nerdy student Lance in front of the monkey habitat. Principal Flutie breaks it up, but Lance covers for the group. They like what he did and they want to show him the hyena house.
Buffy, Willow and Xander are worried for Lance, so they follow the group to help. Xander stops Kyle and his friends from throwing Lance into the hyena pit. A hyena's eyes start glowing and Xander, Kyle and the three others begin to laugh.
Willow admits to Buffy she has a crush on Xander. Buffy admits to being attracted to Angel. Xander arrives and he's acting strangely; he sniffs Buffy.
Kyle and his friends arrive at The Bronze; they stare Xander down before picking on another student.
Buffy stops a pig from running around Sunnydale High. Principal Flutie unveils the pig as the official mascot of the high school.
Willow is tutoring Xander in math, but he's acting erratic. He throws the textbook in the trash and leaves in a hurry. When he passes Buffy in the hallway, the mascot starts freaking out in fear.
During a rain day, the gym class is forced to play dodgeball. Buffy outlasts everyone on her team, but the pack (Xander, Kyle, Heidi, Rhonda and Tor) turn on Lance by hitting him with balls.
Xander drops geometry and insults Willow. Buffy confronts him, but the pack only laughs at her.
The pack attacks and kills the Sunnydale High mascot.
Buffy and Willow are worried about Xander and his behavior. Buffy goes to Giles for help, but he thinks it's natural for a teenage boy. She makes the connection that it all started when the group went into the hyena house. Giles believes they're being possessed by animal spirits.
Buffy confronts Xander. She needs to talk with him, but she knocks him out. They cage him in the library.
The pack attacks and kills Principal Flutie. They nearly attack a mother walking with her baby.
Giles and Buffy chat with the zoo's attendant about the hyenas. The plan is to reverse the possession; however, they realize the pack is going to go back to free Xander.
Xander is freed by the pack. Willow runs and hides in the school.
The zoo attendant is revealed to be evil. He channeled the spirits and created the mark that summoned the possession; he knocks out Giles and uses Willow as a hostage. The attendant recites incantations to steal back the spirits/powers from the pack.
Buffy knocks the attendant into the pit and the hyenas kill him.
Xander fakes having amnesia after being possessed. Giles agrees to keep his secret.