Despite the enthusiastic anticipation of the city's residents for Halloween, a series of horrifying child abductions make their way to Portland, quickly spoiling the holiday spirit. Nick and Hank join forces with Valentina Espinosa, a mysterious detective from Albuquerque, to help find and capture the elusive suspect. Juliette joins their investigation, acting as the precinct's fill-in Spanish translator. The more Nick digs into the case, the more he realizes the pattern of the kidnapping matches those in the famed Hispanic horror story "La Llorona," a story with its roots intertwined with his own family's history. Meanwhile, Monroe celebrates the holiday in fine style as he teaches the neighborhood bullies a lesson.