The Man in the Iron Mask (1939)
Tyrannical King Louis XIV learns that he has an identical twin brother, Philippe, who was raised from birth by his late father's trusted friend D'Artagnan and his faithful musketeers, Porthos, Athos and Aramis. After Philippe falls for the king's betrothed, Spanish Princess Maria Theresa, Louis imprisons him, forcing his brother to don an iron mask that will slowly suffocate him -- and it's up to D'Artagnan to rescue him.
Directed by: James Whale
Starring: Louis Hayward, Joan Bennett, Warren William, Joseph Schildkraut, Alan Hale, Walter Kingsford
Links: IMDb, Movie posters, Movie stills