And those letters?

Dostoyevsky

In a sparse and inhospitable land, the policeman Enzo Vitello, a man with a dark past, is obsessed with "Dostoyevsky", a serial killer whom he kills with a peculiarity: next to the body, the murderer always leaves a letter with his desolate and very clear vision of the world, of life and darkness that Vitello hears resonating in him.