As Paris, swept for weeks by pouring rain, prepares to face the "flood of the century", Marion falls into an ambush and is shot. Hit in the head, she falls into a coma. At the scene, the body of a dealer who served as his informant was also found. In the general chaos of a city disorganized by the natural disaster, Marion disappears from the emergency room. Her lieutenants, Valentine Cara and Luc Abadie, then did everything possible to find her. But the flooding of the Seine has other surprises in store for them...