The elderly couple Delcroix is found brutally murdered. At first, it looks like a robbery. But why were some valuable items not stolen? Something seems off, and Philippe Lagarde is tasked with getting to the bottom of it. This is his most emotional case, as the murder victim was his mentor for many years, and they were close. Did Bertrand Delcroix witness something that cost him his life? During his investigation, Philippe Lagarde uncovers unimaginable depths. Intense investigations in the Bay of Biscay.