Dolmen

Murders in... is a collection of French-Belgian police TV movies taking place each time in a different French city and region.

Clara takes her daughter and her friends to a weekend visit at her grandfather's village. They all have a great time, but after they return home people start dying. First Clara's grandfather mysteriously drowns, then the children start getting sick and one, her goddaughter, dies. Around same time clients at the spa she teaches aqua-aerobics start getting sick with one dying. She finds some mysterious algea, related to Caulerpa taxifolia, planted near where her grandfather supposedly drowned. Clara suspects the algea and all of these illnesses and deaths are related to some sort of poisonings of fish caught near her Grandfather's village.

Marc Lagnier confesses to the murder of his adored son, but refuses to explain.

The corpse of a woman appears in a cave near the sea in Saint-Jean-de-Luz. Captain Marie Daguerre will investigate accompanied by the Commander Becker, a rough Parisian that proves to be the father of the main suspect, in turn disappeared.