When a girl is kidnapped, Jackie and Danny suspect her drug-addicted boyfriend is responsible; Erin's relationship with her boss takes a step forward.

When Danny is put on modified assignment after an incident in which a cop--who failed to identify himself--is shot, he faces Internal Affairs investigators, who are looking to his state of mind on that day for further implications.

When a man’s family is robbed and beaten in front of him, and the assailant is shot and killed, the Reagan’s debate about how far they would go to protect their family. Meanwhile, when a college student is arrested at a rally, Frank wrestles with her sentence due to her identity.

Danny believes a serial killer is on the loose when two separate murder victims are identified as members of a group charged with a gang rape. Meanwhile, Erin’s ex-husband, attorney Jack Boyle, resurfaces in her life as they face off in court.

When a knife-wielding attacker dressed as Baron Samedi, the Spirit of Death, stabs a man in costume on Halloween, Danny enters the world of voodoo. Meanwhile, DCPI Garrett opens up to Frank about a dark secret, and Erin and Nicky take Jack and Sean trick-or-treating.

When two Wall Street brokers are killed in drug deals, Danny looks to question a wounded accomplice at the hospital but he is stopped by Linda, who won’t let Danny see him until after surgery. But when the accomplice dies during the procedure, Danny and Linda battle over the judgment call.