A dangerous criminal from Danny's past comes back to seek revenge and kidnaps Jackie. Meanwhile, Jamie meets his new partner, while a young officer is shaken after he accidentally shoots an innocent man.

A woman recants a domestic-abuse claim, but Danny and Jackie continue to investigate the situation. Soon they uncover the woman's secret affair with a powerful politician who's friends with Frank. Meanwhile, Linda returns to the workforce, causing chaos at home.

Danny and Jackie set out to investigate the murder of a bride on her wedding day in a drive-by gang shooting. However, they are pulled off the case and assigned to the protection detail of a Central American president, who they believe is a target for assassination. Meanwhile, Jamie questions his partner Vinny’s methods when he performs an unjustified stop.

Shortly after Frank awards a detective with the Medal of Valor for his undercover work for the NYPD in Malaysia, the detective is taken hostage by a Malaysian drug lord whose brother he helped put in prison. Meanwhile, Henry goes on a ride-along with Jamie and has a different method of getting the job done.

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.

Danny arrives at a college campus to find a murdered student, who was thought to be dealing drugs. Meanwhile, Jamie has a life crisis when he reconnects with a former law school classmate and Erin must learn to give Nicky some freedom.

When Danny and Kate come up empty-handed with leads for a shooting, Linda helps make a break in the case when she overhears the victim telling his priest who is responsible. Meanwhile, Henry is mugged at an ATM, which sends Jamie into a rage as he tries to track down the assailant.

When an armed robbery ends with the death of a police officer, Frank makes it a mission for the NYPD to bring the suspect to justice. However, tensions run high in the Reagan household when Erin drops the charges and releases the suspect due to lack of evidence.

Danny becomes the lead hostage negotiator when a prime informant in a large drug case holds Erin at gunpoint inside the courtroom.