It is the late 1940s in New York and Don Vito Corleone is the head of a powerful Mafia family. Michael, a free thinker who defied his father by enlisting in the Marines to fight in World War II, has returned a captain and a war hero. Having long rejected the family business, Michael shows up at his sister's wedding, Connie, with his non-Italian girlfriend, Kay, who learns for the first time about the family business.