Arnaud, a 25-year-old man, enters the campaign team of a candidate for the French presidential election as assistant to the Director of communication. While discovering the techniques, intricacies and rivalries of the electoral campaign, he will feel fascination for this world, as well as for its attractive director, Agnès.

In 1852, the mountain village in Provence where Violette lives is brutally deprived of all its men after the repression of the republicans ordered by Napoleon III. Women spend months in total isolation, desperate to see their men again. In this situation, they make an oath in case a man arrives in the village.

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.