A Swiss businessman is found drowned in Lake Geneva. The corpse was ballasted with a Flottins sculpture symbolizing a fantastic creature. According to the local myth, the Flottins saved a few inhabitants from drowning. The murderer uses this legend to kill. The origin of the victim forces the French cop in charge of the investigation, Louis Jolly, to form a team with Sandrine Zermatten, a Swiss cop. A race against time begins to find the killer while Louis figures out that the presence of Sandrine is not that random.
