The newly-named Emperor Maximillian (Brian Aherne), the only monarch of the Second Mexican Empire, arrives in Mexico in the early 1860s with his wife Carlotta (Bette Davis) to face popular sentiment favoring Benito Juarez (Paul Muni) and popular demand for democracy. With an elite group of Mexican monarchists, Maximillian tries to appease the democratic Mexicans but he fails. Abraham Lincoln continues to support Juarez and asks the French to withdraw support for Maximilian. Carlotta goes to France to plead with Napoleon III (Claude Rains), to no avail.—Ed Stephan
Louis Napoleon III (Claude Rains) takes advantage of the American Civil War to circumvent the Monroe Doctrine and expand his power by helping Emperor Maximilian von Habsburg (Brian Aherne) to add Mexico to his empire.