Jo has discovered who was targeting Mathilde. But before she can alert anyone, Sainclair is taken hostage. Jo has no choice but to rush to his rescue alone, at the risk of her own life…

After Mathilde's new attack, everything seems to blame Darzac. But Jo can't believe he hurt Mathilde. The chrysanthemum she found in the crypt takes her to a new trail, that of Roussel, a serial killer who has been dead for years.

When the prime suspect is found dead, all eyes turn to Darzac. Betrayed by Sainclair, Jo teams up with Larsan to solve the mystery. But Mathilde seems determined to settle the score herself, even at the risk of her own life…

Mathilde mysteriously disappears from the hospital. A manhunt is organized for Max Bret—the prime suspect in the kidnapping—while Jo and Sainclair conduct their own parallel investigation. Larsan then decides to stage a nighttime reenactment at Le Pin Noir, bringing all the suspects together.

Mathilde wakes up in the hospital but is unable to say who attacked her. Jo and Sainclair conduct their own investigation alongside Larsan, questioning villagers to find the culprit. Their suspicions fall on a resident who had previously gone unsuspected...

Jo is stunned to learn that Mathilde, a close childhood friend, has been the victim of an attempted murder. The circumstances of the incident are mysterious: when villagers managed to enter the victim's room, she was alone. But where could the attacker have gone?