Mock trial advisor dies tragically during a competition. Meanwhile, Angela's increased interest in selling brownies has Jane concerned that she may be hiding financial issues. And Tommy hires a lawyer to settle his claim against the Storrow Center.

When a kidnapper who dresses as a clown reemerges in Boston after more than 20 years, the squad is struck with fear. Desperate for clues, they dig through files from the unsolved abductions of the haunting 1988 "Summer of the Clown." Meanwhile, as Jane's relationship with Casey becomes more serious, they are forced to face the fact that one of them will have to compromise if they are to take things to the next level. Maura also finds herself in a dilemma when she inadvertently gets in the middle of another relationship.