When a failed drug bust leaves the Undercover Unit with a dead dealer high class prostitute holding a couple of bags of cocaine, the Unit undertake an operation inside a busy brothel: Gotham City.

Working with criminal profiler Vicki Quinlan and the new Head of Homicide Frank Callahan, the Undercover Unit investigate a serial murderer but their attempts to trap the killer leaves Mackenzie fighting for her and her best friend's life.