Nash and Caitlin go undercover as swingers to bust a couple who prey on wealthy swinging couples. Joe and Boz help Nick recover the corpse of an old friend to whom Nick made a war time promise.

Nash pursues a deadly arsonist who torches a church and the only witness is Angel. Caitlin investigates Evan on a police brutality charge, probing into his past. Nash's friends and family plan a surprise birthday for him.