Nights of Tehran (2001)

Best friends Shirin and Mina are sociology students who spend their time analyzing crime and violence in Tehran in an attempt to understand the dark side of society. One day Mina goes missing and ends up the fifth victim of an unknown serial killer. Angry and desperate for answers, Shirin begins her own investigation, determined to bring her friend's killer to justice at any cost. But what kind of dangers is this book-smart girl getting herself into? And could it possibly be that the killer she is hunting isn't as far away as she thinks? A tense and compelling mystery that delves into the darkest corners of the human soul.