Off the coast of Montpellier, a diver exploring a wreck uncovers a highly sought-after treasure: a golden statuette of Medusa, the monster from Greek mythology. The day after his discovery, the young man's boat is found adrift, with no one on board. Has the curse surrounding the legendary statue struck again? Or is a rival treasure hunter behind the diver's disappearance? - It's up to Police Captain Guillaume Le Guen of Montpellier's regional crime squad and his brother, Gendarmerie Captain Damien Le Guen, to solve the mystery. There's no time to waste and they'll need all their investigative skills, particularly because the victim is none other than Thibault Gagneur, Guillaume's son-in-law, whose daughter Emilie is expecting his grandchild.