Lise Stocker and Clovis Bouvier must face a new and completely new threat. Many people are afflicted with a mysterious and deadly disease. A virus is spreading in Annecy. A race against time is underway to find the origin of this virus and try to stop its spread. Was it an accident? A criminal act? Terrorist? Is this virus linked to the mysterious disappearance of a little girl and her father? Every minute counts because already the number of victims is increasing... Spin-off of the series "The Mystery of the Lake" and "The Lake Killer".