The novel opens on October 3, 1951, when a boy named Cotter Martin sneaks in to watch the New York Giants play the Brooklyn Dodgers at the Giants' home field Polo Grounds. (The prologue, Pafko at the Wall, was written on its own before the novel.) In the ninth inning, Ralph Branca pitches to Bobby Thomson, who hits the ball into the stands for a three-run homer, beating the Dodgers 5-4 and capturing the National League pennant. Known to baseball fans as "The Shot Heard 'Round the World", the fate of that ball is unknown, but in DeLillo's novel, Cotter Martin wrests this valuable ball away from another fan who has just befriended him, and runs home. Cotter's father, Manx, steals the ball and later sells it for $32.45.
Branca and Thomson are never given much screen time, and Jackie Gleason and Frank Sinatra only put in cameos, but other historical figures become important parts of the story. J. Edgar Hoover muses on death, loyalty and leather masks while comedian Lenny Bruce faces the Cuban Missile Crisis by impersonating a hysterical housewife shrieking, "We're all gonna die!"
Early in the novel it is revealed that Nick Shay was in a juvenile detention center for murdering a man, but it is not until near the end of the book that we learn the details of his crime. After being released from the detention center, he is sent to a Jesuit reform school in northern Minnesota.
In the epilogue, we learn that Nick and Marian remain married despite infidelity on both sides. In fact, Nick indicates their relationship is much improved as he has opened up to her about his past – a subject that had always much interested her − and that he had been unwilling to discuss.