Louis XIII, King of France, had a son, Louis, who succeeded his father to the throne. But, known to very few, the heir had a twin brother, Philippe, hidden away after birth and forced to languish in prison, his identity unknown behind an iron mask. His brother, now grown and King Louis XIV, proved to be both corrupt and a tyrant. Louis sends Athos' son, Raoul off to certain death in war, so that he could have his woman for himself. Athos, together with two of the other Musketeers, Porthos and Aramis, swear revenge. Only D'Artagnan remains loyal to the crown, but will he join his former compatriots to free Philippe from prison, kill the king, and put Philippe on the throne in his place?
