Audrey, Nathan and Duke are lured to a haunted house on Halloween - and become trapped inside.
Walt and the team cross county lines to find a killer who left its victim in a compost heap; Branch investigates Cady's abrupt departure.
What was meant as a much-needed night off for Bo grows into a scavenger hunt in a lawless Dark Fae territory. In Bo’s absence, Trick is placed in a precarious position with potentially dire consequences.
After realising her goals align with her former enemy, Sarah forms an alliance. Meanwhile, Felix and Donnie infiltrate a fertility clinic.
Sarah and Rachel must come together for the greater good. Cosima and Susan disagree about the ethical implications of human experiments.