In 1936, twelve-year-old Aldo Trapani witnesses his father getting gunned down on the street by the Barzinis, the Corleones' rivals in New York. Don Vito Corleone comforts the child, telling him when he has grown up and the time is right, he can take revenge for the death of his father. In 1945, at the wedding scene of Don Corleone's daughter, Aldo's mother asks Don Corleone to look after her son, who has been hanging out with the wrong people. Luca Brasi is sent to recruit Aldo and teach him the ways of the Mafia.

Luca sleeps with the fishes. Tom Hagen, Corleone Consigliere, has disappeared. Can anyone stop the Tattaglias from destroying the Corleones? Clemenza has discovered where Sollozzo is hiding Tom, but his motives are unclear. With Don Vito's recovery uncertain, a long shadow is cast over the fate of the Corleones.

The hospital is deserted - Tessio's men have been sent away, and only a few guards remain. Inside, Don Vito lies helpless to the destiny that awaits him... Despite pressure from corrupt local cops, Rosa fronts a Corleone brothel out of her Flower shop. It's New Years Eve, and Frankie's out of town...

With Don Vito still recovering, Sonny Corleone has a hunch about who betrayed the Godfather. He orders Clemenza to get the job done... Sollozzo is exploiting the chaos within the Corleone family and has started up a drug smuggling operation in Midtown. Clemenza has a plan to strike back.

Jack Woltz is blackballing Don Vito's godson, the famous singer Johnny Fontane. Tom Hagen is sent to deal with Woltz and make him an offer he can't refuse... The streets are full of tension; Sollozzo and his dirty cop McClusky call a meeting...

Sonny takes the war to the streets, aggressively expanding the 'empire'. A terror on the streets, Sonny must also take care of the Family at home... Sonny has put Carlo in his place, and is guiding operations with a mighty fist. The Tattaglias are in ruins, but they still fight on - whose bloody hand is secretly controlling them?

1955: With Michael in charge and ready for revenge, Don Vito's negotiated peace with the Five Families is fragile and everyone is on edge... With the death of Don Vito, the Corleones appear weak. Tessio approaches Michael with a deal from Barzini as the old Don predicted: the one with the deal would be the traitor...

Casino mogul Moe Green has prospered under the Corleone's protection. But his growing power stands in the way of Michael's ambitions in Las Vegas... ...on the day of the Baptism, it has begun. With Tessio and Moe Green dead, Michael makes demands on Family loyalty like never before. Now is the hour...

With all the Dons dead, Aldo takes the war to their compound finally putting an end to their empire and claiming New York to the Corleones.