Creepy Child: Billy Underwood. He may not even be a child but a spirit trying to help the cops find his killer.
Foreshadowing: Doggett's involvement in this case is being driven by his own son's kidnapping and murder.
Paedohunt: It is implied that Cal Jeppy has at least molested Ronnie Purnell and Billy Underwood and killed Billy. He also almost gets to Billy's brother Josh but fails.
Wrong Genre Savvy: Averted. Doggett insists on treating Billy Underwood's reappearance as a standard child kidnapping, even through Scully keeps pointing out the strangeness of the case. Doggett, however, succeeds in resolving the case.