Scott and Stiles discover that the werewolf curse can also be triggered by anger, besides the full moon. With the lacrosse game coming up, Jackson and his girlfriend, Lydia, hope to humiliate Scott. Will Scott be able to control his rage?

Allison's aunt comes to town and shoots a shadowy werewolf figure with a special bullet that she estimates will kill it within 48 hours. Derek is the one hit and insists that Scott and Stiles help him.

Responding to Scott's howl, the alpha savages Derek and traps Scott and Stiles in their high school. Events escalate even further when Allison, Jackson, and Lydia are lured to the school as well with a phony text message.