Nadat een studente op klaarlichte dag is neergeschoten, blijkt uit het onderzoek dat ze meer dan een paar geheimen had. Ondertussen krijgt Jane's moeder Angela ruzie met haar vader over de auto.

De Boston Marathon verandert in een plaats delict wanneer een schutter zich op lopers begint te schieten. Jane en Maura racen om de moordenaar te pakken te krijgen voordat andere worden neergeschoten. Jane en Maura moeten hun onderzoek in het geheim uitvoeren om geen massale paniek te veroorzaken.

Jane and Maura investigate a family's background when a man is killed; Jane suspects that Maura is hiding something.

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.

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.

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.

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.