Detective Enzo Vitello becomes obsessed with tracking down the serial killer "Dostoyevsky". The killer has a habit of leaving letters next to the bodies of his victims describing their last moments. Seduced by the killer's nihilistic notes and driven by his own demons, Vitello begins a secret correspondence with the killer. This exchange drives Vitello to the dark corners of his soul and forces him to face a secret from his past - a secret that led him to abandon his daughter Ambra when she was a toddler.