Blue Bloods is a drama about a multi-generational family of cops dedicated to New York City law enforcement. Frank Reagan is the New York Police Commissioner and heads both the police force and the Reagan brood. He runs his department as diplomatically as he runs his family, even when dealing with the politics that plagued his unapologetically bold father, Henry, during his stint as Chief. A source of pride and concern for Frank is his eldest son Danny, a seasoned detective, family man and Iraq War vet who on occasion uses dubious tactics to solve cases with his loyal and tough partner, Detective Jackie Curatola. The Reagan women in the family include Erin, a N.Y. Assistant D.A., who also serves as the legal compass for her siblings and father, and single parent to her teenage daughter Nicky; and Linda, Danny's supportive wife. Jamie is the youngest Reagan, a recent grad of Harvard Law and the family's "golden boy." Unable to deny the family tradition, Jamie has decided to give up a lucrative future in law and follow in the family footsteps as a cop.
Danny contemplates retiring until Erin enlists him to help her with a case involving her ex-husband, Jack. Also, Jamie and Eddie go undercover as a couple, and Frank butts heads with the new mayor of New York City, Margaret Dutton.
Frank receives an order from the mayor to attend a parade honoring a man who served time for conspiring in an attack against the police. Meanwhile, Danny investigates the return of a teen who suspiciously disappeared 13 years ago; and Jamie and Eddie help a young woman they believe is being exploited by a congressman.
Erin's trial against a notorious human trafficker is jeopardized when the presiding judge is mysteriously found dead. Danny and Baez are put on the case to investigate foul play. Meanwhile, Mayor Dutton opposes Frank's public safety initiative, but City Council Speaker Regina Thomas devises a plan to help Frank bypass the mayor's veto.
Danny and Baez work the case of a detective who was gunned down prior to testifying against a career criminal. Also, Frank personally investigates when Garrett is attacked by a SWAT team outside his home, and Erin brings in a confidential informant against Anthony's wishes.
Danny and Baez investigate the murder of a single mother whose ex-husband has a history of violence. Also, Frank deals with the fallout when Mayor Dutton eliminates solitary confinement in prisons, and Jamie's efforts to save a young woman who overdosed on drugs has unexpected consequences.
When a famous basketball player is found dead of an apparent drug overdose, Danny looks into his possible ties to a local drug gang. Also, Erin revisits the case of a man she may have wrongfully convicted years ago, and Frank is approached by Archbishop Kearns regarding an eviction matter Jamie and Eddie are working on.
A case turns personal for Danny when he works to protect a nurse, Faith Madson, from her violent ex-boyfriend. Also, Shelly Wayne, an acquaintance of Frank's, comes to him with a theory regarding the death of an inmate, and Jamie and Eddie help deliver a baby.
Eddie's judgment is clouded by her past when she arrests a loathed acquaintance from college on questionable charges. Also, Frank is hesitant to mar the spotless record of a member of the force, a decorated U.S. military veteran, who tested positive for marijuana.
As Danny and Baez join a narcotics task force to track down a drug supplier, Baez comes into contact with drugs and is soon fighting for her life from an accidental overdose. Also, Jamie and Eddie work to protect a rehabilitated sex offender whose neighbors are angry he lives in their apartment building, and Frank forms an unlikely alliance with Mayor Dutton.
Erin is conflicted when Jamie and Eddie ask her to help drop old charges against a man, Parker Mack, who just bravely rescued a woman from a local hostage situation. Also, Danny and Baez work a case involving car thieves and discover the leader is Victor Lugo, a mobster they've dealt with before, and Baker receives a job offer.
When a journalist disappears while working on an exposé about an innocent man serving time for murder, Danny and Baez hope that reexamining the original case will help find her. Also, Frank reluctantly speaks out against an initiative led by Erin's office to consider drug abuse as a disease first, and a crime second.