Madrid, 2011. The warmest August in man's memory. Half a million pilgrims await the pope's visit and the city is under surveillance of security forces. A number of older women are suddenly murdered. Two police commissioners, Velarde (Antonio de la Torre) and Alfaro (Roberto Álamo), who no one wants to work with, is tasked with clarifying the murder mysteries. But it turns out to be harder than that and the thrill of the film increases as we as the audience get to know who the serial killer is and follow this in his deeds.