Doug is an American mining engineer. Pres. Valdez of Paragonia (Aitken) wants him to reopen the countrys mines. Doug is not interested ... until he sees the Presidents beautiful daughter, Juana (Rubens). Valdez returns to Paragonia, but is deposed by Generals Sanchez and Garcia and locked in San Mateo Prison. The Americano arrives. His companys local office has been ransacked, but he finds loyal caretaker Dan (Wilson) in hiding there. He is contacted by former Prime Minister Castille, now in disguise as a peddler... Valdez writes the mysterious date 23 Noviembre 1899 on scraps of paper which are then thrown from the prison window as garbage. Juana checks her fathers diary. That date contains an account of a successful escape from San Mateo, using the secret tunnel! But Garcia demands that Juana marry him the next day or Valdez will die...