After getting a match from an unknown relative from a DNA network, Sean Reagan does some detective work to figure out who this mystery person might be. Frank gets a personal request from a woman to transfer her son to a safer assignment. Also, Danny seeks to uncover the truth behind the murder of a key witness in one of Erin's cases, and Eddie begins to think about having a child after she and Jamie discover a newborn left outside their precinct.

Danny and Baez are faced with tracking down a drug dealer after two young models are found dead from an overdose. Also, Eddie and Jamie team up to determine who the mastermind is behind a robbery.

Erin and Anthony trust a sociopath who claims he has evidence to convict a murderer; Frank faces backlash from his department when he suspends an officer for violent behavior; Danny and Baez try to arrest a notorious gangster.

Frank and Garrett devise a plan to convince Mayor Chase to work better with others in order to properly run the city, and Danny and Baez try to track down a perp who vandalized several NYPD vehicles with anti-cop graffiti and made threats against officers. Also, Erin is shaken after she's in a car accident, and Eddie and Jamie argue about whether they should keep a stray dog who leads them to a crime scene.

Jamie is under investigation after his police vest is found on a perp. Frank debates whether to aid and protect an old friend whose home was invaded. Danny and Baez investigate the suspicious circumstances surrounding the death of a hotel employee believed to be a suicide. Erin asks Anthony to make a deal with a man who knows secrets about the current D.A.

Danny and Baez work with Texas Ranger Waylon Gates when they are put on a case to find the Lone Star Killer. Also, after Eddie's partner, Officer James Addison, mistakenly shoots an undercover cop, internal affairs accuses Jamie of not supervising properly, and Frank speaks with Officer Addison about why he shouldn't turn in his shield.

Frank must uncover the truth when an undercover officer accuses a fellow cop of police brutality. Also, Danny and Baez investigate the murder of a famous photographer recently accused of assault by his former models, and Erin struggles to protect a witness as new justice reform laws go into effect.

A widow blames Frank for her husband's recent suicide; Eddie has a gut feeling about a murder; a desperate Luis Delgado wants protection for his sons.

After an EMT is shot and killed, Danny and Baez work to determine who is behind a chain of ambulance robberies; Frank defends New York's homeless community after the mayor puts a new law in place; Eddie offers to help Jamie pay off his student loans.

After a woman is found dead at a men's-only club, Danny and Baez investigate if her death was an accident; Frank hears about an alleged affair between the chief of Internal Affairs and the spouse of another member of law enforcement.

Erin disagrees with a psychiatric consultant's diagnosis of a nanny accused of abuse; Eddie confronts her boss; Frank is forced to make staffing changes he is skeptical about; a woman claims she heard someone plotting a murder.

While Henry works as an investigative consultant for child services, he and Danny butt heads over a case involving a man who is volatile toward his wife. Frank is caught in the middle of an ongoing battle between the NYPD and the FDNY. Erin ponders a life-changing opportunity presented to her by Mayor Peter Chase. Jamie is suspicious about an investigation targeting Eddie's partner.

Jamie and Frank oppose each other's viewpoints over the public's treatment of cops after rowdy teens pour water on two rookies. Danny and Baez investigate a man who preys on the elderly. Erin is forced to admit her wrongdoings.

Frank is conflicted about how to deal with former cop Rick Austin’s gripe about his pension. Jamie helps a friend, Connor O’Brien, deal with illicit pictures of his daughter on the internet. Danny hunts down a killer who shot his online prison pen-pal. Anthony confronts the realization that his foster son, Sam, might not be suited for police work.

Frank works to vindicate Detective Douglas McKenzie, a detective accused of using excessive force. Also, Danny and Baez track down the killer responsible for the death of a rapper’s bodyguard. Jamie is skeptical about a relationship between Espinoza and a new rookie officer, Sarah Brooks; and Eddie goes undercover to help Erin investigate a mysterious cult.

Frank takes one of Jamie’s cases to heart when it involves the suspicious death of his friend’s, FBI Agent Wilson Ortega’s, terminally ill wife. Also, after demanding more meaningful cases, Erin receives an unsolved robbery case that proves to be impossible to crack without help from Anthony, and Danny and Baez uncover the shocking truth behind a puzzling assault claim.

Frank's esteem for an old friend proves to be a mistake; Jamie asks Erin for help apprehending a perp who shot at him after learning she chose not to send him to prison six months ago; Eddie clashes with her new boss.

Frank and Erin are at odds when Frank learns the D.A.’s office keeps a list of “unreliable” cops. Also, Danny and Baez recruit retired mobster Vincent Rella to assist in an investigation, and Jamie participates in a decoy operation to take down a predator posing as a ride-share driver.

Danny and Baez grapple with a homicide investigation brought to their attention by Maggie, the medium who previously helped them solve a case; Frank looks for a way to help his ex-partner Lenny Ross when Lenny's daughter gets arrested.