The series is loosely inspired by the Dutroux affair, which occurred in Belgium in the mid-1990s.
The series was greenlit following a 2013 call for projects by Belgian TV group RTBF which garnered 150 submissions. This and The Break (2016) are the first two series to come out of it.
In the closing credits: "figurant" is the French word which means: "extra"; a performer with no speaking part.
The writers took inspiration from True Detective (2014) and Breaking Bad (2008) to craft the series.
To create the character of Guy Béranger, the writers were inspired by No Country for Old Men (2007)'s Anton Chirgurh and Schindler's List (1993)'s Amon Goeth as examples of realistic psychopaths (unlike Hannibal Lecter).