Abraham Reynolds, a good samaritan is killed when he stops a clown from kidnapping a boy. It is reminiscent of a case that occurred in 1988.
Another child is kidnapped and video of the child and clown are sent to the police. The team manage to track it down to Brent Miller's home where they find the boy unconscious but OK and Miller dead of an apparent suicide.
Tests show that Miller was drugged but he was probably the kidnapper from 1988. Going through the old case files, detectives find a vicim who was molested. The DNA under Reynolds's fingers belongs to his older brother. The brother was there the day of the molestation and recognized Brent Miller's voice when he came into his store. He set up the new abductions to point towards Brent and then killed him making it look like suicide.
Det. Frost is upset at Maura for encouraging his girlfriend to take a job in China but they eventually make up.
The Army is offering Casey a promotion to General and he and Jane are torn over which one of them should give up their job for the other. He gives Jane an engagement ring but then he has to leave earlier than expected. Jane doesn't know whether to say yes or no to his proposal.