Growing up in Lawless, Angelo Lagusa witnesses the brutal murder of his family by the Vanetti mafia. Adopting a new identity, Avilio Bruno, he patiently waits for the perfect moment to avenge his loved ones. A mysterious letter draws him back to Lawless after seven years, where he befriends Nero, the son of the Vanetti don, to execute his vengeful plan. Set against the backdrop of the Prohibition era, 91 Days follows Avilio's calculated and grim journey as he methodically eliminates each accomplice in his family's tragedy.