Autumn in Provence: A gloomy, rainy November - and a dead hiker is found in the middle of Lac du Paty. Police captains Caterine Castel and Alain Theroux investigate. The victim was a well-known property mogul. Did his dubious business dealings have anything to do with his death? But then a tip lands in the letterbox of ex-commissaire Albin Leclerc. Apparently there is a serial offender behind it, who calls himself Darkness and has been playing a gruesome game undetected for years. And this perpetrator is challenging Albin to catch him. The prize: the Leclerc family. It's a matter of life and death, and Albin is running out of time...