In the 17th century, under Louis XIII, the policy of Cardinal de Richelieu aimed at the definitive establishment of a monarchic power, and gave rise to a struggle against the great feudal lords, who favored a weak central power. Numerous conspiracies against the Cardinal were led by the high nobility. The one led by Henri Coiffier de Ruzé d'Effiat, marquis de Cinq-Mars, was the last and most famous of them.

One hot afternoon in the south of France, several paths are converging towards a tragic conclusion. Those involved are: Stéphane and Luigi, two cousins who have just emerged from adolescence; Georges, a retired old man; Amélie, Luigi’s girlfriend; and Amélie’s mother Anne. Little do they know how their lives, scarred by fear, humiliation and weariness, will become intertwined and propel them to a terrible outcome...