Fed up with the the insufferably cruel behavior of Louis XIV (Richard Chamberlain), a group of musketeers plot to replace the king with his twin brother, Philippe (also Chamberlain). They kidnap Phillipe and temporarily lock him in the Bastille, where he is inevitably recognized as a dead ringer for Louis. Word gets back to the king and, fearing for his safety, he decides to have his brother locked in an iron mask and subsequently imprisoned for life.