Scott and Malia get help to try to find Hayden and Liam. Deaton discovers something horrific about the dread doctors. Hayden and Liam will be faced with a life and death situation.
Scott, Malia, & Stiles scramble to find a way to save Sheriff Stilinski from an unknown toxin while Liam & Mason search for the whereabouts of Hayden's body and the other dead chimera bodies.
After finding out that Lydia is in danger, Stiles makes a plan to break her out of Eichen House; Theo has his own plans as he joins Deucalion in a quest to kill Scott.
The Pack are trying to figure out how to defeat the Beast of Gévaudan that the Maid of Gévaudan, Marie-Jeanne Valet, faced in 1765. As Gerard Argent, recounts Valet's story to Scott's pack in hopes they can deduce the creature's weaknesses.