Supernatural: Season 4, Episode 14

4 - 14: Sex and Violence

Sam and Dean enter a small town in Iowa, where three men have inexplicably beaten their wives to death. The guys realize that behind the murders is a Siren, a creature that can take different forms and desperately needs love and compels people to destroy themselves as a show of devotion. The Siren eventually puts Sam and Dean under their spell and pits the two brothers against each other in a fight to the death.