"The Rookie" Season 4, Episode 5, titled "A.C.H." and airing on October 31, 2021, is a celebrated Halloween special featuring a city-wide crisis caused by a designer drug that mimics a zombie outbreak. The Mid-Wilshire team must manage the violent, "infected" citizens while Officer Lucy Chen investigates a potential haunting in her apartment. For more details, visit CBR . THE ROOKIE Season 4 Episode 5 Photos A.C.H. | Seat42F