Lou Gehrig, [Gary Cooper], is a young Columbia University student whose old-fashioned mother wants him to study engineering, but the gift for baseball is strong. A sportswriter befriends Gehrig—Sam Blake, played by Walter Brennan—and persuades a scout to come see him play. When his mother falls ill, Gehrig signs with the team he has always revered, the New York Yankees, to help pay the hospital bills, trying to keep the career change a secret from his mother, with support from his father.
Gehrig works his way up from the minors to the Yankees. His hero, Babe Ruth, is at first condescending toward the rookie, but Gehrig's steady, reliable play wins over Ruth and the rest of the team. Ruth’s initial sarcasm yields to respect as Gehrig displays a quiet, relentless excellence. Gehrig is unknowingly drawn into playing pranks on Ruth during train rides, a lighthearted dynamic that humanizes the star-studded clubhouse.
During a game at Comiskey Park, Gehrig trips over a stack of bats and is teased by a spectator, Eleanor Twitchell—Teresa Wright—who later becomes properly introduced, and a romance blossoms. Eleanor’s flirtation eventually deepens into engagement, though Gehrig’s mother remains wary of his shift away from engineering toward baseball. Gehrig finally stands up to her and marries Eleanor, cementing his choice to follow his dream.
The Yankees emerge as a dominant force, with Gehrig becoming a fan favorite. His father and his mother attend games to cheer him on. In a moving gesture, Gehrig visits a crippled boy named Billy in the hospital; David Holt portrays Billy, and Gehrig promises to hit two home runs in a single World Series game in the boy’s honor—then fulfills the vow, a moment that deepens his legend.
Gehrig earns the nickname “Iron Horse” as he rides a peak of national adoration, supported by a wide circle of friends and a devoted wife. Yet his body begins to betray him, and he notices a troubling decline in strength. He continues to play and even extends his consecutive-game streak, but a doctor delivers terrible news: a rare, incurable disease that gives him only a short time to live. He benches himself after expressing his concerns to Yankees manager Joe McCarthy, Harry Harvey.
A short time later, on Lou Gehrig Day at Yankee Stadium, an older Billy returns to remind him of the triumphs his courage inspired. Eleanor—Teresa Wright—weeps softly in the stands as Gehrig delivers a farewell speech to the fans. In the end, a moved crowd and a grateful city witness the moment when Gehrig speaks his iconic line:
> People all say that I've had a bad break. But today ... today, I consider myself the luckiest man on the face of the Earth.
