Frank works to vindicate Detective Douglas McKenzie (Mike Carlsen), 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.

Jamie and Frank oppose each other's viewpoints over the public's treatment of cops after rowdy teens pour water on two rookies. Also, Danny and Baez investigate a man who preys on the elderly, and Erin is forced to admit her wrongdoings when Jack brings her an old case and claims a man she put away was falsely convicted.