Unbeknownst to his family, Frank must deal with a potential biological weapon's attack on New York City as they celebrate Mother's Day. Danny and Jamie's long standing dispute comes to a head.
The death of a free spending and extravagant investor looks suspicious to Danny and Jackie. Jamie is placed under house arrest when a hit is placed for "Jimmy Riordan".
Danny and Jackie discover a leak in the NYPD after an attempt is made on their witness in protective custody. Erin has a chance to work with Frank when she's offered the job as deputy mayor.
When a 12-year-old boy insists Danny reinvestigate the suicide of his firefighter father, his gut tells him to listen. Jamie's heroic actions at a building fire have him concerned his undercover work could be put at risk.
A gun buyback program has a "no questions asked" rule but when a gun returned is linked to a robbery, Danny must decide whether to follow the rule or arrest the suspect.
While Erin is prosecuting a murder case, the defendant's attorney is murdered. Danny is assigned to investigate but things get tense when Erin questions Danny on the stand.
A high-profile reporter, who happens to be a close friend of Frank's, is in town and almost assaulted. Jamie's undercover case reaches a critical stage.
Danny and Jackie investigate the murder of a Reagan family friend who was an undercover detective. Danny's family starts to worry as the persistent search takes an emotional toll on him.
After family is robbed and beaten and the assailant is shot and killed, the Reagans discuss how far they'd go to protect their family. Frank is conflicted with charges brought against a girl arrested at a rally when her identity is revealed.
After a wealthy woman dies of a heart attack, Danny and Jackie must investigate when her daughter claims God told her that her stepfather actually murdered her mother. When the archbishop comes asking for Frank's support for the canonization of a local priest, Frank decides to check into a rumor about the priest back when he protested the Vietnam War.moreless
While out in the car with his family, Danny becomes involved in a shooting when a man running from a gunman crosses the path of the car. Frank says goodbye to an old partner and friend.
Danny and Jackie investigate when a uniformed officer is seen fleeing the scene of a murder at a diner.
Danny and Erin must work together to find out who killed her informant.
To obtain leniency for his son, an ex-mobster helps Danny on some cold cases. Jamie is working undercover to find a secret about the Sanfino family.
Henry's heart attack on Thanksgiving eve leaves the family contemplating a future without him. While Danny and Jackie look into a suicide that may not be what it seems, Frank and the mayor disagree about a threat to the city.
When a killer starts targeting prostitutes, Jackie goes undercover as an escort. Erin meets a guy whose interests coincide with hers.
A political crisis ensues following a 911 call at a religious center. Jamie and Renzulli are injured when they attempt to enter the center to respond to the call.
Even while on a case, Danny tries to swing a romantic weekend with Linda. Jamie's undercover assignment involves a crime family.
Frank made an arrest in a rape case 18 years ago and Erin decides to reopen the case. Danny and Jackie have to deal with the murder of three teenagers for which there appears to be no motive.
Danny discovers that a former cop is one of the men who attempted to rob a bank. Jamie gets a new partner.
Internal Affairs starts an investigation after Danny accidentally shoots a cop. The big question they look into is his personal state of mind at the time of the shooting.
When one of the Mayor elect's supporters, who's also the husband of Erin's close friend, is found dead in his car, the Mayor pressures Frank to play it as a random act of violence. Meanwhile, Jamie goes on his first undercover assignment.