Beast's Obsession

S15, E20: The sadistic William Lewis (Schreiber) escapes from prison, arbitrarily killing as he goes. Concerned for Benson's safety, a security detail is assigned to her 24/7, but it doesn't take long for Lewis to get her back where he left off. With time running out, Benson must decide how much she's willing to sacrifice in order to save the life of a child.