Investigator Enzo Vitello, a man and father with a dark past, investigates Dostoevsky, a killer who always leaves a letter with his vision of the world next to his victims.

Vitello secretly exchanges messages with the killer, while trying to deal with the drug problems of his daughter, Ambra, abandoned years before.

Vitello follows the clue in the last letter and explores the trail of former orphans. When the letters are released to the press, Vitello is betrayed and his investigation compromised.