With the school under attack, and Parrish leaving, Gerard tells the story of the Beast to Lydia. Marie Jeanne (Special guest star Crystal Reed) is the first Argent to have killed the beast. Knowing what materials were used brings them a step closer to killing it. Scott finally as a scent that brings him to the bloody shoes that they were looking for. Liam and Scott discover with horror that Mason is the Beast. Corey brings Mason away, not knowing what he his getting himself into.