Based on an original idea by best-selling Danish novelist Elsebeth Egholm, the series follows the inquiries of a special unit at Copenhagen's police force, consisting of detective inspector Katrina Ries Jensen and forensic psychiatrist Thomas Schaeffer. The pair specialise in serial killers that do not fit within traditional behavioural patterns.

Investigator Jan and profiler Louise constantly move around in the thrilling periphery of a murderer's view as they link a series of killings.