When a mutilated sex offender is found dead, it is unclear if he was the victim of a hate crime, sexual assault or self-mutilation. As Intelligence questions those related to the case, they find themselves up against a private "special police" force who may be covering up illegal activities.

The district is in a state of change - Lindsay has moved to New York- and the CPD is under scrutiny about the corrupt nature of its institution. Under the watchful eye of the city, the team attempts to bust a gun deal that quickly turns dicey when innocent civilians and children get involved. Tension erupts when Chief brings in Denny Woods to review the shootout, and Halstead becomes a key player in the outcome of the case.

One of Voight's friends, Congressman Scott Graynor is found passed out in his hotel room with a dead Ukranian girl. When Intelligence discovers the murder is connected to a sting and Burgess' boyfriend is working with the Feds, Burgess must choose between compromising her case or her boyfriend's case.

Voight and Ruzek lock horns over how to handle the aftermath of the Antonio situation. Meanwhile, a series of violent carjackings turns deadly, and Ruzek must rely on a C.I. he grew up with to help solve the case.