Jackie Estacado is a hired killer for the Franchetti crime family, which is run by his uncle Paulie. After years of the two not seeing eye to eye, Paulie now wants Jackie dead. He sets it up so that Jackie can be blamed for some missing money and then tries the blow him up. With both Mob and cops gunning for him, Jackie discovers that he is possessed by an entity called the Darkness. A monster of great power that protects and helps him but it is also is trying to control him. Jackie does not have time to decide if it's a blessing or a curse, Jenny is now in danger. She is his true love; they grew up together in an orphanage before Paulie rescued him. Can he shield Jenny from the true about what he does and what is happening to him? Can he kill his uncle before Paulie and his men gun him down? What is the Darkness, and why did it pick Jackie?