Aurélie Lelièvre, in her forties, ornithologist and author of best-selling popular books on nature, uses a spectacular and ingenious staging to kill her husband Robert Lelièvre, 50, a gynaecologist-obstetrician and director of a successful clinic. He is found dead at the edge of his swimming pool, his skull smashed by a turtle that fell from the sky. Agnès and Thibaud are called to the scene to see clearly in this more than strange death.
