Thought Criminal

S15 E23: Under the guidance of Lieutenant Murphy (Donal Logue), Sergeant Benson (Mariska Hargitay) and the SVU take an active approach to catching sex offenders - they target Simon Wilkes (guest star Joshua Malina), a well-regarded photographer with a secret life. An undercover investigation finds his graphic fantasies may have crossed the line into reality, at a child's expense. But the case becomes impossible when no evidence of a victim is found, so Detective Amaro (Danny Pino) takes matters into his own hands.