S4, E13: 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 “Summer of the Clown” in 1988. Meanwhile, as Jane’s relationship with Casey (recurring guest star CHRIS VANCE) 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.