What's the worst that can happen to a police officer? Definitely an unresolved investigation. This is what happens on Boxing Day 1999. Charlotte Meyer, an 11-year-old girl, disappears without a trace. Captain Pierre Castaing, in charge of the investigation, fails to find her. Where did she go? The mystery remains intact ... A few hundred kilometers away, a young investigator finds herself confronted with a similar disappearance ...

The story revolves around the people of Sète, France. Their lives are punctuated by family rivalries, romance and scenes from daily life, but also by plots involving police investigations, secrets and betrayals.