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.

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.