The body of an examining magistrate is found in the Bois de Saint-Cloud, poisoned with aconite, an extremely toxic flower commonly known as "wolfsbane." Novak is certain that the victim's profession led to his death. The tale of the wolfsbane plant troubles Julia, especially as other elements of the investigation recall the story of Little Red Riding Hood. Despite initial disagreements, Julia and Novak converge in their deductions, and hand in hand, they embark on this investigation, more united than ever. However, this doesn't prevent Novak from simultaneously conducting a personal investigation into Julia. Since the revelations about their breakup 25 years ago, Novak has been obsessed with what Julia told him. He attempts by all means to discover the secret that kept her away from her friends and family when she was 18.