In 1945, amidst the bustling energy of his daughter Connie’s wedding to Carlo Rizzi, Vito Corleone, the revered and feared Don of the Corleone crime family, listens to requests for favors. Among those seeking his influence is Johnny Fontane, a famous singer and Vito’s godson, who begs for help securing a coveted movie role. Vito dispatches his trusted consigliere, Tom Hagen, to persuade the film’s studio head, Jack Woltz, to comply. When Woltz resists, he awakens to the gruesome sight of his prized horse’s severed head in his bed—a message impossible to ignore.
As Christmas nears, the Corleone family faces a new challenge. Virgil “The Turk” Sollozzo, a drug baron allied with the rival Tattaglia crime family, proposes a partnership in his narcotics trade, seeking the Corleones’ political and police connections. Vito, wary of the risks to his reputation, declines. Suspecting treachery, he sends Luca Brasi, his loyal enforcer, to infiltrate the Tattaglias. Brasi’s mission ends in betrayal and his brutal murder.
Shortly after, Vito is ambushed and shot in an assassination attempt orchestrated by Sollozzo. Though he survives, his incapacitation thrusts his hot-headed eldest son, Sonny, into command. Sollozzo, alongside corrupt NYPD Captain Mark McCluskey, pressures Hagen to convince Sonny to accept the drug deal. Meanwhile, Michael, Vito’s youngest son and a decorated World War II Marine who has distanced himself from the family business, visits his father in the hospital. He finds Vito unguarded, the result of McCluskey’s interference, and thwarts a second attempt on his father’s life, though he is severely beaten by McCluskey in the process.
Sonny retaliates, launching an attack that kills Bruno Tattaglia, escalating tensions between the rival families. Sollozzo and McCluskey propose a truce and request a meeting with Michael, who volunteers to attend despite his family’s objections. The Corleones devise a daring plan: a hidden gun is planted in the restaurant where the meeting is held. After a tense conversation, Michael retrieves the weapon and executes both Sollozzo and McCluskey, marking his violent entry into the family’s shadowy world.
The murders spark an all-out war among the Five Families. To escape the fallout, Michael flees to Sicily, where he finds solace and love, marrying a local woman named Apollonia. Back in New York, Sonny’s temper flares when Carlo abuses Connie. After Carlo repeats the offense, Sonny races to confront him but is ambushed and gunned down at a toll booth in a savage attack orchestrated by rival families. In Sicily, tragedy strikes again when Apollonia is killed in a car bomb intended for Michael.
Grieving and weary of the endless bloodshed, Vito arranges a meeting with the Five Families. Swallowing his pride, he agrees to let go of vengeance for Sonny’s murder and withdraws opposition to the narcotics trade, hoping to bring peace. With his safety guaranteed, Michael returns to New York to assume a greater role in the family. He marries Kay Adams, his college sweetheart, and they begin a family, raising two children as Michael grows into his role as Vito’s successor.
As Vito’s health declines, he reveals to Michael that their true enemy has always been Don Barzini, who manipulates events from the shadows. Vito warns Michael of an impending betrayal within their own ranks, advising him to be vigilant. With his father’s support, Michael reorganizes the family, appointing Hagen to oversee operations in Las Vegas, a move signaling the shift of power to the West Coast.
Michael’s leadership is tested in Las Vegas, where he attempts to buy out casino owner Moe Greene. Tensions rise when Fredo, Michael’s older brother, sides with Greene over his own family, exposing Fredo’s weakness and lack of loyalty.
In 1955, Vito dies of a heart attack while playing with his grandson, Michael’s son Anthony. At the funeral, Tessio, a trusted capo, reveals his betrayal by arranging a meeting with Barzini under the guise of reconciliation. Michael, now the Don, uses the opportunity to strike. As Tessio is led away to be executed, Michael meticulously orchestrates a series of hits on the heads of the Five Families. While he stands as godfather at the baptism of Connie’s child, his men eliminate Barzini, the other rival dons, and even Moe Greene, solidifying Michael’s power and control.
With his rivals vanquished, Michael confronts Carlo about his role in Sonny’s death. Carlo confesses, believing Michael’s assurance that his life will be spared. However, as Carlo is escorted away, Clemenza garrotes him in a car, marking the final act of vengeance.
Connie, devastated, accuses Michael of orchestrating Carlo’s murder. Kay, overhearing the confrontation, privately questions Michael about the truth. He denies involvement, offering her a false sense of relief. Moments later, as Kay watches from a distance, Michael is addressed as “Don Corleone” by the family’s capos, a door literally and figuratively closing on her as Michael fully embraces his father’s legacy.
