Jack Crawford and his team are confronted with a serial killer who believes that he is possessed by a Japanese fox spirit, a Nogitsune.
As the murders continue, Will realizes that they are all connected to one of their own. Agent Derek Hale was in some way or another involved with all victims, which leads Will to believe that the killer must be close to Agent Hale. In fact Will thinks that the killer is reaching out to Derek, sending him some sort of twisted love letter.
Supported in this theory by FBI consultant Hannibal Lecter, Will and Derek start a dangerous game of cat and mouse with the killer; a young man called Stiles.
Obsessed with Derek, Stiles turns out to be a dangerous foe to deal with and even a man as dangerous as Hannibal might just have met his match. When Hannibal finds out that Derek has a boyfriend and suggests protective custody for him, he summons Stiles’ rage upon himself. But with Derek’s boyfriend Mason already taken by Stiles, things are way more out of control than even Hannibal had anticipated. A final confrontation is inevitable as time is already starting to run out for Derek’s boyfriend…