Based on the true story of Saeed Hanaei, a serial killer who targeted street prostitutes and killed 16 women from 2000 to 2001 in Mashhad, Iran, the film depicts a fictional female journalist investigating a serial killer.

A journalist descends into the dark underbelly of the Iranian holy city of Mashhad as she investigates the serial killings of sex workers by the so-called Spider Killer, who believes he is cleansing the streets of sinners.