Ten years after the death of her son Esteban, Maddi meets Tom, a young boy who looks strikingly like him. Intrigued, she moves from her native Basque country to be closer to Tom in Auvergne. A series of murders rocks the peaceful region. Are these events linked to her son's death?

When Tom is the victim of a serious accident, Lazare's investigation focuses on Jonas, the boy's father. Maddi shares a disturbing discovery about Tom with Sabine and Nectaire. The link to Esteban is obvious; could Jonas be linked to his death ten years earlier?