Captain Rojas arrives in northern Chile from Santiago to investigate the mysterious disappearance of a group of teenage girls in Alto Hospicio.

Intelligence confirmed by the head of the Alto Hospicio police forces Rojas and Carrasco to travel to Tacna, a wild Peruvian city on the border with Chile. In Peru, Rojas infiltrates the people-trafficking gangs who deal in “white slaves” in an attempt to find the missing Chilean girls, to no avail.

After reviewing all the murders of women in the area, Captain Rojas believes he has found his serial killer’'s "Case Zero": a prostitute, whose body appeared on a beach two years ago. While Rojas pursues this lead, Carrasco has suspicions about a volleyball teacher who taught several of the missing girls. The information spreads amongst the neighbours, who want to take justice into their own hands

Following the trail of disappearances leads Rojas to 'La Ponderosa' a place in the middle of the desert where private parties are held with prostitutes, many of whom are minors.

The case of the Alto Hospicio Psychopath reaches national coverage, but Rojas' investigation into institutional corruption in Hospicio puts him in the sights of several powerful men in the area.

Rojas leaves the hospital after receiving a brutal beating in which Carrasco also secretly participated. The attempt to intimidate Rojas only reinforces his need to continue investigating, but his theory crumbles when the innocence of the driver of La Ponderosa, whom he considered the main suspect, is proven

After exposing the corruption and threatening his superior, Rojas continues his investigation without the support of the police.

Rojas is convinced that he has discovered the identity of the psychopath but he has no evidence. He travels to the murderer's hometown, where he discovers the origin of his violent instincts.