When a new designer drug hits LA streets, it turns users into "zombies," and Officer Nolan and the team have a Halloween they won't soon forget. Back at home, Lucy questions whether her apartment building might be haunted.

In the aftermath of Fred's house explosion, Officer Nolan and Bailey discover there's more to Fred's death than meets the eye. Meanwhile, Officer Chen and Officer Bradford demand a treasure hunt rematch and enlist Officer Grey to help set the terms to a new bet, all while they arrest a series of wealthy female criminals. Elsewhere, Wesley struggles to keep it together under the pressure of his debt to Elijah.