As Frank contends with a whistleblower within the NYPD, Danny and Baez investigate a suspicious case originally written off as an accident.
The team joins forces with the Special Operations Bureau when an elderly couple is shot in their home and a killer prowls Los Angeles taking hostages along the way.
The Major Crimes division works to stop a serial killer who has been targeting female sex workers, Captain Raydor seeks the help of a consultant and Stroh gets closer to achieving his deal.
Phillip Stroh returns, demanding a new deal from DDA Rios in exchange for his cooperation. Meanwhile, Major Crimes races to prevent the deaths of three women while trying to decode the source of Stroh's information.