The lifeless body of a 60-year-old woman is discovered on the beach of Alycastre in Porquerolles. Elisabeth Carlson was a painter and admired person on the island. Her body at the foot of the cliff evokes the Lycastre, the famous dragon from the legend that gave the bay its name. Arnaud Taillard (45 years old), the very serious deputy prosecutor who is native to the country, will have to lead the investigation with Charlie Buczkowski (47 years old), a capricious police commander recently transferred from Seine Saint-Denis. However, it is quickly revealed that Arnaud's family is no stranger to this matter.