1x6 - Vanished by the Lake

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?