Stiles checks himself into a mental hospital called Eichen House to keep everyone safe from the nogitsune controlling him. Meanwhile Scott and the pack search for an ancient Japanese scroll that could explain how to destroy the nogitsune and save Stiles.
Scott’s friends vow to protect him from the mysterious shadow warriors while Argent, Isaac and Allison track down a past adversary of Argent’s who may have some insight into the masked specters. Meanwhile Stile turns to Nurse Melissa McCall to help him figure out what is going on with him.
The town-wide power outage plus enforced curfew throw a wrench in Danny’s plans for a black light Halloween party. Ethan and Aiden come up with a solution – but Derek is not going to like it. Meanwhile, the shadow warriors are confronting the members of the pack one by one, leaving trauma in their wake.