A frail, asthmatic young Theodore Roosevelt transforms himself into a vigorous champion of the strenuous life, loses one great love and finds another, leads men into battle and then rises like a rocket to become the youngest president in American history at 42. Meanwhile, Franklin Delano Roosevelt, brought up as the pampered only child of adoring parents, follows his older cousin's career with worshipful fascination and begins to think he might one day follow in his footsteps.

Murder brings Theodore Roosevelt to the presidency, but in the seven years that follow, he transforms the office and makes himself perhaps the best-loved of all the men who ever lived in the White House - battling corporate greed and building the Panama Canal, preserving American wilderness, carrying the message of American might around the world. FDR courts and weds Eleanor Roosevelt, the shy orphaned daughter of Theodore's alcoholic brother, Elliott. Together, they begin a family. Franklin enters a law firm, but when he is offered a chance to run for the New York state senate, he jumps at the chance.

Theodore Roosevelt leads a Progressive crusade that splits his own party, undertakes a deadly expedition into the South American jungle, campaigns for American entry into World War I - and pays a terrible personal price. Franklin masters wartime Washington as Assistant Secretary of the Navy, while Eleanor finds personal salvation in war work. Her discovery of Franklin's romance with another woman transforms their marriage into a largely political partnership. TR's death at 60 is almost universally mourned, but provides Franklin with a golden opportunity.

Franklin Roosevelt runs for vice president in 1920 and seems assured of a still brighter future until polio devastates him the following summer. He spends seven years struggling without success to walk again, while Eleanor builds a personal and political life of her own. FDR returns to politics in 1928 and, as governor of New York, acts with such vigor and imagination during the first years of the Great Depression that the Democrats turn to him as their presidential nominee in 1932. He survives an attempted assassination as president-elect and at his inauguration tells his frightened countrymen the only thing they have to fear is "fear itself."