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In the 20th episode of Law & Order: Special Victims Unit season 15, " Beast's Obsession ," escaped serial rapist William Lewis initiates a killing spree, kidnapping a child to force a final confrontation with Olivia Benson. The episode culminates in a high-stakes psychological game where Lewis forces Benson into a deadly situation before taking his own life to frame her. [S15E20] Beast's Obsession