不要轻信陌生人的糖。精产国品一二三产区区别在哪

　　A serial killer is terrifying the prostitutes in a big Italian city. After few barbaric murdering four prostitutes Lena, Angela, Nadine and Stella decide to unify and try to self-defend themselves. The police and all the other prostitutes agree with the four and the hunting is open. Who is the cruel killer?