Longwy, an abandoned steel factory, under the broken glass roofs, children play with their slingshots: The door of an old metal cupboard, ends up yielding, to their great joy …… which turns into dread when they discover the skeleton hidden inside inside. Clara, Guillaume and François arrive on the site: The body is quickly identified, it is Hervé Chaumont, a former steelworker, union activist and one of the main presenters of the free radio "Lorraine heart of steel", voice of labor protest in the 70s and 80s. A few days later, two other former steelworkers and radio hosts were also murdered.