Xander and Cordelia are making out in Cordy's car when they are interrupted by the vicious attack of a werewolf. Giles is intrigued by the idea of a werewolf in Sunnydale - one of the classics - but intrigue turns to concern as he and Buffy encounter a hunter named Cain who wants to kill the werewolf for it's pelt, and then a Sunnydale High student named Teresa is found dead. As the Slayerettes try to figure out who the werewolf might be - Xander's theory that's it's Larry, one of the school jocks, turns out to be very erroneous - Willow tries to determine why Oz s acting so weird.
When she goes to his house to confront him, she finds him transforming into a werewolf. Buffy, Giles and Willow manage to bring the werewolf down and keep Cain from killing their friend.