An Unhappy Happy Is a Dangerous Thing (S01E04)

Harry and Fergus decide to assist a local loan shark, Happy, in uncovering the identity of his employee's murderer. In exchange, Happy will erase the significant debt that Fergus's father owes him. As Harry investigates, she discovers connections between the murder and Dostoevsky's "Crime and Punishment," which ultimately draws the interest of aspiring serial killer Billy Lund.