May 1993. Two sisters, Alice, 20, and Amber, 21, are found dead on the banks of the Garonne. Dressed in their first communion dresses, they sat facing each other, tied to two trees. Young Martin Servas, who has just joined the Toulouse police, conducts his first interrogation. Very quickly his attention is drawn to Erica Lang, the famous author of cruel and frightening thrillers. Weren't his sisters fans of his? Isn't one of his most successful novels called First Communion? But suddenly things take a completely different turn...February 2018. On a cold night, writer Eric Lang discovers his wife murdered... and also dressed in the dress of the First Communion. After 25 years, Martin Servas resumes the investigation. But he still doesn’t know that the past, which has become the present, will turn into a nightmare for him. A nightmare written in black ink...