I saw this at Cinequest, the San Jose Film Festival in March of 2006. The story is about a middle-aged detective, beaten down by life and bureaucracy, until he seems just barely able to pull himself through each day. He's also a drug addict, smoking something, but I'm not sure if it's hash or opium. He's investigating a series of murders of prostitutes in the slums of Tehran? The movie is in Farsi, with English subtitles, so I didn't catch all the details.
What makes this movie different from the other 100 serial killer of prostitutes being pursued by a burnt out detective movies you've seen is it's presentation of the physical and cultural deterioration of Iran. The rain-soaked scenes in the ancient alleyways look like something out of Blade Runner, except this isn't some sci-fi fantasy, but modern reality. There's a religious school that figures in the story and the rituals that these disciples engage in are truly frightening, particularly the lengths they go to for self-punishment and repentance.
It's relentless in its portrayal of corruption and cynicism at the higher levels of society, even as those at the lower depths literally give their lives for their piety. Not all those in power want the killings to stop because they're "cleaning up the city".
This movie is chilling in its portrait of a culture deconstructed by religious fundamentalism and it will make you despair of being able to reason with those fundamentalists at the heart of the Islamic Jihad.