Riding in an open-topped convertible through Dallas on November 22, 1963, Vice President Lyndon B. Johnson heard a sudden explosive sound at 12:30 P.M. The Secret Service sped him away to safety, and at 1:20 P.M. he learned that JFK had been assassinated. Here historian Steven Gillon tells the story of how Johnson consolidated power in the twenty-four hours following -- actions that determined the tragic outcome of his presidency.