Set in the 1990s, the series follows the disappearance of a local teenager, Stella, which reopens old wounds for Clémence Rosier, the last CEO of the MTLK factory before it closed down. Her son Benjamin's unsolved death two years prior is now tied to the case, and Clémence is forced to team up with Antonio D’Ambrosio, a factory worker long suspected of being involved in her son’s death. The duo must decode a mysterious book written by the two children, uncovering secrets that threaten to destroy the fragile community.