Teen Wolf: Season 3, Episode 9

3 - 9: The Girl Who Knew Too Much

Allison and Isaac learn that the Darach is planning to sacrifice guardians next, they think that her father is involved with the murders, but end up discovering that he has been tracking the Darach for a while now. Meanwhile, Scott and Stiles want to use Lydia to solve the murders. Lydia discovers that Jennifer Blake is the Darach; Jennifer is about to kill her, when Lydia screams and she realizes that Lydia is actually a banshee, aka "the Wailing Woman"; this explains her attraction and inclination towards the supernatural. Stiles' dad tries to save Lydia, but is kidnapped by Jennifer, as he is a guardian. Scott goes to Ms. Morrell for some guidance; Morrell reveals that Deucalion's plan for him is that either Scott will join the Alpha Pack willingly as a True Alpha, or Deucalion will force Scott to kill, destroying his potential to become a True Alpha.