After investigating a grisly murder, clues lead Nick and Hank to a seemingly unstable father who is on the run with his daughter. As they learn more about the case they realize that the girl's father may be the least of their worries. At the spice shop, Monroe finds out filling in for Rosalee isn't as simple as he'd hoped it would be. Meanwhile, Captain Renard finds himself paying unwarranted attention to more than one woman from his past.

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.