Le mystère du lac

Lise Stocker, head of the Paris Crime Bureau, returns to her hometown to care for her sick mother. Upon her return, she hears that local teenager, Chloe, has vanished during a local celebration. The mystery disappearance ignites old memories for Lise - fifteen years ago her two best friends, Ana and Marion, disappeared during the very same event. Is there a connection between the two incidents?

Lise's mother's ill health is an increasing worry and the primary suspect in Chloe's disappearance is on the run. Determined to prevent history repeating itself, Lise joins forces with the local cops, led by Detective Clovis, to help solve the case. Lise realizes that she is involved in a double investigation, finding out what happened to Chloe may also explain what happened to Ana and Marion.

Remi Bouchard is arrested over Chloe's disappearance, just like he was fifteen years ago. Lise is not sure he is guilty, especially when he informs her that the former prosecutorial investigation against him was biased and certain elements were left out. The investigator at that time was none other than Lise's own father, who has since committed suicide. Who is lying and who is telling the truth?

Several locals become suspects: Chloe's father Herve is questioned by the police, Thomas seems to be in an increasingly suspicious position as does Ana's brother, Hugo, who had a relationship with Chloe - a violent one. Lise and Clovis's investigation appears to indicate that Remi Bouchard is telling the truth - the investigation led fifteen years ago was falsified, but to protect who?

There is a major break-through in the case and it becomes apparent that it's the same perpetrator today as it was fifteen years ago. Remi Bouchard's alibi is solid and Clovis must release him. Suddenly, Lise is struck by the obvious, what if the guilty party was someone close to her, even closer than her own father?

Suspicions soon points to Chloe's former teacher, Nicolas Mazaud. Evidence against Mazaud, who also taught Ana, Marion and Lise is getting stronger and stronger. Was Clovis wrong to release Remi Bouchard who appears to be a step ahead of everyone in solving the mystery puzzle? And does a letter of confession really mean Lise and Clovis have found the culprit?