Police Captain Tess Borski is back in the Pas-de-Calais with her husband and daughter. Visiting a mining site with her daughter, she discovers, with the group, the body of a notable of the region. She is in charge of the investigation with Commissioner François Dubois. The investigation brings the Courrières disaster back to the forefront. Is there a relationship between the 1906 disaster that cost the lives of 1,099 miners and this new death that was rehabilitating the mining sites?