A body is found in a state forest. As the head and hands were burned, it is impossible to identify the victim, so Lea relies heavily on the help of Franck, the pathologist. The murder weapon found in the pyre is a tool used by foresters, loggers and forest guards. Would the murderer be one of them ? Zoé, Franck's sister, who is a forest guard, knows the place well and offers her help. But during the investigation, Zoé mysteriously disappears.