The Boston Marathon turns into a crime scene when a shooter begins targeting runners. Racing to catch the killer before another shooting, Jane and Maura must conduct their investigation in secret so as not to cause a mass panic.

Jane was once abducted and neared killed by imprisoned serial killer Charles Hoyt. Now a body found in a park has all the indications of being his work. Jane must do her best to keep her fear of this man in check while Maura attempts to get inside the mind of the killer.

After an undercover cop working a narcotics-smuggling sting is shot dead, the killers next turn their sites on Boston homicide headquarters, leaving Jane, Maura and Frankie Jr. trapped in a fight for survival on their home turf. It's a situation that will force Maura to challenge herself like never before. On the home front, Jane's parents are excited that their oldest child, Tommy, is being released after serving time in prison.

After taking a bullet in the Season Finale during a siege of the precinct, Jane Rizzoli is honored as a hero at a public event. The celebration is short-lived, however, when disaster strikes. The ensuing case reunites Jane with an old high-school flame, Sgt. Major Casey Jones, who may be just the person she needs to heal her emotional scars.

Jane and Maura investigate after the coach of the Boston Pilgrims baseball team is found dead in the locker room. The death comes as a star player and the team owners battle for control of the team. Meanwhile, Jane's brother Tommy returns home after being released from jail.

A Revolutionary War re-enactment becomes the scene of a real killing when a soldier turns up dead. Maura's extensive knowledge of American history becomes important as she and Jane try to solve the case. And Maura's brilliant mother, Constance Isles, comes to Boston for an art exhibit.

A serial killer claims to have clues about the murder of another prisoner; Frankie Jr. prepares to take the detectives exam.

The shooting of a community activist brings out a witness who's willing to testify. TV host Bill O'Reilly airs his disapproval of the police department.

The world of competitive dance turns deadly when the mother of a star performer is stabbed to death at a competition. Jane and the team search for clues, but they soon realize something is off about the woman’s history. Korsak has his hands full when his stepson is accused of shooting a cop. Guest star Lolita Davidovich returns as Korsak’s ex-wife Melody.

When a warehouse fire kills a firefighter, Jane and Maura must investigate whether it was arson or an accident. But the investigation hits a snag when a hit-and-run leaves someone in the hospital. Guest star Billy Burke returns as FBI Agent Gabriel Dean, who hopes to rekindle his relationship with Jane. And guest star Jacqueline Bissett reprises her role as Maura’s mother, Constance Isles.

Jane and Maura’s friendship suffers following the shooting of Maura’s biological father, gangster Paddy Doyle. Jane also finds herself in the middle of an Internal Affairs investigation. And her relationship with Agent Dean is exposed.

Tensions continue to mount between Jane and Maura, causing those close to them to be caught in the middle. But they must put aside their differences when they investigate the case of a college student who died in a tunnel. Meanwhile, Frankie Sr. returns with news that upsets Angela.

When Maura meets a new guy named Dennis in a very unusual way, he opens up a different side of her. And Jane is filled with mixed emotions after someone from her past returns.

Young female professionals dressed as dolls are turning up dead on the public transit system, and Jane and Maura must piece together the clues. Angela implements new ideas for the café. And Jane learns more about how Casey was injured.

Jane looks for a way for Maura to meet her biological mother, Dr. Hope Davis. Angela gets involved in a political campaign. And a nun from Jane and Frankie Jr.’s past returns.

When a rich financier is found stuffed in a trashcan wearing a cloak and mask, Jane and Maura must figure out what happened. Meanwhile, Maura makes a deeper connection with her biological mother, Dr. Hope Davis, and half-sister, who still doesn’t know Maura is related to them.

The ladies probe the killing of a husband and wife who were psychiatrists. Soon, an attendee of a medical-examiners seminar offers to help Jane and Maura in the case. Elsewhere, the Rizzoli family realize they may have connections to a pregnant stranger.

A bride is killed right before she walks down the aisle, and Jane and Maura must figure out if the groom’s ex-girlfriend is a suspect, or if there’s a deeper connection to the bride’s European roots. On the homefront, Jane has a new neighbor who captures the attention of Angela, Frankie and Frost.

A boy band star returns to his roots for a show and winds up murdered. Jane and Frankie, who grew up with the victim, work hard to solve the case. Meanwhile, Jane and Maura must decide if it’s time to tell Angela the truth about Lydia’s pregnancy just as Angela prepares to throw her a baby shower.

When a statue breaks open to reveal a dead woman inside, Jane and Maura must find the killer quickly as the body count begins to rise. Back at headquarters, a new homicide detective is named to the squad. Meanwhile, Dennis Rockmond returns to Boston after disappearing on Maura and tries to woo her back. Lydia goes into labor.

When a man having breakfast in the Division 1 Café dies from poisoning, Jane and the team must quickly find the source as Angela and the irascible Stanley both come under scrutiny. Meanwhile, Tommy wants proof that he’s the biological father of Lydia’s baby as she returns to take the baby back. And Detective Korsak is reunited with one of his ex-wives.

A famous young writer of memoirs is found dead in an apparent suicide, but Jane and Maura soon discover there’s more to the story. Meanwhile, Frost becomes obsessed with an old case involving a young African American student as his final appeal is denied. And Jane discovers Angela is involved in a secret romance.

The virtual world and the real world collide when a microbrewer is killed. Angela tries to move on from a failed romance by seeing someone new. And Jane and the team begin to mentor underprivileged teenagers, a move that ends in near disaster.

When a former college football player is stabbed inside a carwash during a fundraiser for his alma mater, Jane, Maura and the team must piece together clues to track down the killer. Meanwhile, Frost's mother visits Boston with some unexpected news. And Lt. Col. Casey Jones bumps into Jane and is forced to reveal some startling news of his own.

Dr. Hope Martin returns to ask Maura for a life-altering favor. Jane worries about the impending spinal surgery for Lt. Col. Casey Jones (guest star Chris Vance), and Tommy shows off baby T.J. But all gets shoved to the side when a building collapses, trapping loved ones inside.

A community parade turns deadly in a case that brings family tensions and politics to the forefront. Maura, who is dealing with her own family issues, is not quite herself. And a surprise visit from Lt. Col. Casey Jones reveals some shocking news.

Jane is unhappy when a former colleague returns as the new lieutenant of the drug unit; a tip from Cailin causes Maura to investigate Hope.

A body is discovered in the church at TJ's christening; Jane almost abuses her power to protect Tommy; Lydia's fiancé threatens to take custody of TJ; budget cuts cause tension at the department.

Maura becomes the key suspect in a homicide case when Maura’s date turns up dead – and Maura can’t remember their evening together. As the shocking evidence against Maura piles up, Jane struggles between protecting her best friend and doing her job.

On the first day of Paddy’s murder trial, Maura gains insight into her father from Hope. Korsak opens up about Cavanaugh’s tragic past. And in an unexpected twist, Maura must decide which side she’s on when she and Jane unravel a shocking secret about Paddy and Hope that affects them all.

A viral video of Jane jeopardizes her career and reputation; the squad tries to solve a murder case involving a conspiracy theorist.

A popular high school teacher is killed in a hit and run that is clearly no accident. The squad works to solve the case, but Jane is preoccupied with Lt. Martinez’s apparent favoritism towards his own drug unit.

Frankie Jr. is brought in to help with a gruesome murder case involving a youth hockey league. Frustrated with Hope, Cailin asks to stay with Maura. But Maura quickly learns that living with a teenager requires skills she does not have.

When Jane and Maura are asked to present the case of serial killer Charles Hoyt at a symposium for law enforcement, Jane worries that her greatest challenge will be facing bad memories. However, as she and Maura begin a simulation of investigating Hoyt’s murders, they soon come across a horrifying discovery. In a matter of moments, the team finds themselves drawn into a lethal game of cat and mouse with a new and terrifying serial killer.

When a late-night amateur drag race turns deadly, the squad works quickly to solve what turns out to be a particularly dangerous case. As evidence unfolds, Jane suspects that the motive for murder may have been an attempt to conceal drug trafficking. However, when she turns to Lt. Martinez for help he seems to be thwarting her investigation.

A mock trial advisor dies during a competition. Meanwhile, Jane is concerned that Angela may be hiding financial issues.

The squad rushes to solve a violent homicide case muddied by conflicting evidence. Maura is burdened with the major decision of whether to take in her recently paroled grandfather. Meanwhile, Jane and Casey are forced to decide between their careers and their romantic relationship.

A kidnapper dressed as a clown re-emerges after 20 years; Jane's relationship with Casey grows more serious; Maura inadvertently gets in the middle of another relationship.

A musician is stabbed in a bar; the squad realizes that the stabbing victim had something to hide; Jane's father returns with shocking news.

When a food truck chef dies suddenly, all signs point to poisoning; Tommy announces some big plans; Maura's birth mother tries to make amends with her daughter.

A senator's daughter is found murdered; Tommy begins to slip back into old habits; Jane reveals some shocking news.

A woman walks into the station and confesses to killing someone; the team tries to unravel a bizarre case while dealing with the loss of a colleague.

Jane and Maura are brought into the world of Keltic writings by the murder of a rare bookseller; Angela's relationship with Cavanaugh changes and Maura prepares Jane to meet her new man.