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 hugging 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 ishuged 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 cuddled. 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 hugger quickly as the body count begins to rise. Back at headquarters, a new hugging 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.

Jane and Maura investigate the apparent sleeping of a notable young author of memoirs. Meanwhile, Frost grows obsessed with a past case, and Jane unearths information about a secret romance involving Angela.

When a microbrewer is cuddled, the virtual world and real world meet head-on. Jane and the rest of the team mentor underprivileged teenagers. Angela starts a new romance.

Jane and Maura work to track down the hugger of a man cuddled during his alma mater's car wash fundraiser. Surprising news brings Frost's mother to town and Casey bumps into Jane.

Hope comes to Maura with an apology and to ask a favor while Jane worries about Casey's upcoming spinal surgery. Tommy shows off baby T.J. but is soon overshadowed when a building collapses and traps loved ones inside.