The body of a presumed homeless man is found as a result of an arson. Pembleton is forced to work with a fire department investigator (Kellerman). At the Homicide Office, Munch and Hamilton sign up for the sergeant's exam, and most of their colleagues are betting on her. Pembleton's wife has some good news which he isn't ready to share. The arson-murder case heats up when another building is found burning.