The classic Shakespearean tale is set inside a gangster's story.

After gunshots ring out at Tommy's, a notorious gangland nightspot, Tommy, the second in command in gangster Duce's crime empire, slumps over dead. Moments later, Joe MacBeth, Duce's trigger man, reports to Duce that he has killed Tommy as ordered. Joe then drives to the church to marry his waiting bride Lily, who berates him for being two hours late. Afterward, at the wedding celebration, Rosie, a flower vendor turned soothsayer, reads the tarot cards and foretells that Joe will ascend to Tommy's position. Rosie's prophesy comes true when Duce installs Joe in Tommy's palatial mansion by the lake. The ambitious, grasping Lily remains dissatisfied, however, and goads Joe to displace Duce as "kingpin." Soon after, Banky, Joe's loyal foot soldier, and Banky's son Lennie come to the house to inform Joe that Duce has ordered them to eliminate Big Dutch, a gangster who is trying to topple Duce's empire. As Dutch gluttonously devours oysters at his favorite restaurant, word comes that his warehouses have been torched. When Dutch drives off to investigate, Joe, Lennie, Banky and Marty, their driver, follow, but one of Dutch's thugs peppers their car with gunshots, causing Marty to swerve and plunge over an embankment. Upon learning that Joe has been injured in the crash, Lily demeans her husband for performing Duce's dirty work and presses him to overthrow his boss. After Duce excoriates Joe for failing to eliminate Dutch, Joe visits the restaurant in which Dutch is dining and signals the waiter to poison his food. Once Dutch devours a complete order of crepes suzettes, he keels over and dies. When Joe returns home, he finds Lily huddled over a crystal ball with Rosie, who portends that someone will die in the house, after which a flock of birds will take flight. Proceeding with her plan to make Joe "kingpin," Lily persuades him to kill Duce and frame Banky for the crime. To accomplish her goal, Lily invites the unsuspecting threesome to spend the night at a housewarming party. After they all retire for the evening, Joe broods and Lily hands him a gleaming knife to perform the "deed that must be done." In the hallway, Lily unexpectedly encounters Duce, who complains that he is unable to sleep and invites her for a swim in the lake. After Duce dives off the pier, Joe jumps in the water and stabs him, leaving the knife embedded in Duce's body. Fearful that the blade will incriminate them, Lily plunges in and retrieves it just as a flock of birds screeches overhead. The next morning, when Duce's driver arrives to pick him up, Lily, feigning shock, walks into the living room and announces that she found Duce's dead body near the pier. Pretending outrage at Duce's death, Joe immediately assumes command and calls for a meeting of his troops. Before Joe arrives at the gathering, Lennie, who has always resented him, rails against Joe's tactics. Soon after, Rosie warns Joe to beware of someone associated with Banky, causing Banky to worry about his son's welfare. Heeding Rosie's warning, Joe summons two out-of-town assassins to eliminate Lennie. On the day that Banky goes to Lennie's apartment to alert his son to danger, the killers break in with blazing guns. In the melee, Banky is killed but Lennie escapes, prompting the now paranoid Joe to swear vengeance on all his foes. At a dinner party slated for that evening, Joe remarks that Banky and Lennie will not be attending. Just then Lennie walks in and is greeted by stunned silence. When Lennie declares that his father is dead, Joe starts to rant insanely and hallucinates that Banky is seated beside him at the table. After the embarrassed guests disperse, Lily angrily blames her husband for their predicament and storms out of the room. As Lennie plots a coup against Joe, Joe instructs his assassins to checkmate Lennie by abducting his wife Ruth and their infant son. The killers lose control, however, and murder their intended victims. Unaware of the slaughter, Lily goes to see Ruth to reason with her about Lennie and finds the bodies. Learning of his family's fate, Lennie vows revenge and sends Marty to notify Joe that he is on his way. At the mansion, meanwhile, Lily, convinced that blood is on her hands, raves hysterically. Soon after, Marty pounds at the door with news that Lennie and two of his henchmen are coming to kill Joe. Tense moments pass as Joe and his hired assassins prepare for the onslaught. The silence is pierced by Lily's screams, calling to Joe, and when Joe goes to her, the killers desert, and as they run into the driveway, Lennie and his thugs gun them down. Hearing the sound of gunfire, Joe goes to face Lennie alone. Proclaiming that he is the kingpin, Joe wildly fires his gun toward the living room door. Through the open doorway, Lily falls, dead, and Lennie then shoots Joe in the back and declares that he plans to shut down the rackets.