With both lives and friendships on the verge of being destroyed, Scott and his pack face their greatest enemy yet.

Scott and Stiles try to learn what is behind the mysterious infection that is killing the town sheriff.

Stiles works on tracking down a fugitive; Liam tries to be Mason’s wingman at a nightclub.

On the eve of senior year, Scott and his pack deal with the arrival of a new enemy and the return of an old friend.

Stiles is suspicious of a new classmate; and Lydia helps a student with night terrors.

Scott tracks a new shapeshifter that’s threatening Stilinski; and Malia receives information about her mother.

Bill wins over Adele’s church group with his vivid recollections from the Civil War; Sam reveals his feelings to Sookie; Jason gives vampire blood another shot with the help of…

As Derek begins his role as interim chief, he faces a potential lawsuit when Bailey and Meredith’s patient awakens from anesthesia mid-surgery. Meanwhile, Teddy refuses to place Cristina on her…