Frank works to vindicate Detective Douglas McKenzie, a detective accused of using excessive force. Also, Danny and Baez track down the killer responsible for the death of a rapper’s bodyguard. Jamie is skeptical about a relationship between Espinoza and a new rookie officer, Sarah Brooks; and Eddie goes undercover to help Erin investigate a mysterious cult.

Danny and Baez are faced with tracking down a drug dealer after two young models are found dead from an overdose. Also, Eddie and Jamie team up to determine who the mastermind is behind a robbery.

Frank causes family tension when he assigns Jamie to guard Danny after a hit is put on him; Frank tries to stop his grandson from seeking revenge after he’s attacked; Eddie gets a hostile new partner.

Danny and Baez team up with Danny's old partner to find a copycat killer emulating a criminal's murders from a previous case; Frank and Mayor Chase battle over how best to handle the city's rising homeless population.