One the eve of the start of senior year, Scott and his pack are challenged by the arrival of a new enemy.

Stiles tries to prove his suspicions about a new classmate; Lydia helps a student who suffers from night terrors. 

Scott tracks a dangerous shapeshifter that has been threatening Stilinski; Malia receives information about her mother. 

Stiles works on tracking down a fugitive; Liam attempts to be wingman for Mason while at a nightclub. 

In hopes of learning more about the Dread Doctors, the pack goes into Eichen House. 

After following Dr. Valack's advice, Scott and the others begin to experience strange things. 

A somewhat awkward teen is attacked by a werewolf, inheriting the curse as well as the enemies. 

Scott and Malia try to rescue captured friends; Deaton discovers something horrific about The Dread Doctors. 

Scott turns to an unlikely ally for help; Styles and Lydia search for the truth about Parrish. 

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. 

Even without the support of his pack, Scott considers what the Dread Doctors' success means for Beacon Hills. 

Kira and her mother make a journey to help Kira deal with her dark side; Lydia is surprised at Eichen House. 

Scott tries to get his pack put back together; Malia and a new ally attempt to rescue Deaton from The Desert Wolf. 

Upon learning that Lydia is in danger, Stiles makes a plan to break her out of Eichen House; Theo has his own plans. 

While trapped in Eichen House with Theo and the Chimera pack, Scott tries to rescue Lydia before time runs out. 

Scott and his pack use a charity lacrosse game in a deadly gambit to figure out the identity of the Beast. 

The Argents reveal a key clue to the mystery of the Beast of Gevaudan in hopes of aligning with an ally; Scott tries to take on the Beast. 

Now that the Beast's identity is known, Scott and the others race against time to stop the Dread Doctors. 

While Scott and the others work to stop the Beast before Beacon Hills is razed to the ground, loyalties are tested and alliances are forged.