Lydia and Jackson witness a werewolf attack at the video store. Stiles is worried for his father, the sheriff. Allison's aunt gives Allison a family heirloom and encourages her to use it to learn more about the family history. Scott and Allison play hooky on her birthday. Derek confronts Jackson about what he saw the night before. Derek gets a surprise visit. At the parent teacher conference, Scott's mom and Allison's father find out they both skipped school that day. After the parent teacher conference, someone pulls a gun and uses it.

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.