Paris,inthe1960s.Aseriesofcrimestroublesthepublictranquility.OnMarch,22,1968,HélènePicard,aprostitutesentencedtodeathtwoyearsbeforeforseveralmurders,iskilledbyexecutionerLouisGuilbeau.Immediately,theviolentcrimes,similartoHélène’sones,goonagain.Inparallel,Louisishavinganaffairwiththepolicewomaninchargeoftheinvestigation…Whataretheobscurerelationshiddenbehindtheexecutionerandthemysteriouskiller?Whoisthisdarkmaninreality?