In an alternative universe, Davy Crocket survived the 1836 siege at the Alamo, and Santa Ana did not. As a result, Texas remained an independent republic and never joined the United States.
In 1947, Texican President Charles A. Lindbergh learns that a flying saucer has crashed near the far west Texas town of Roswell. He dispatches his best friend, "Wild Bill" Bear, and three of his best Texas Rangers, to investigate. Our four heroes find themselves in a race against agents from the United States, the Franco-Mexican Empire, the California Republic, and the Third-and-a-half Reich, to find that crashed saucer and learn its secrets.
And when they do, they will change the course of history, again.