The Man In The Iron Mask (1977)

D'Artagnan and his fellow Musketeers plot to replace the ineffectual Louis XIV of France with his secretly imprisoned twin brother Philippe who is the firstborn and rightful king. Based on the novel by Alexandre Dumas, The Man In The Iron Mask stars Richard Chamberlain, Patrick McGoohan, Louis Jourdan, Jenny Agutter, Ian Holm, Ralph Richardson, Vivien Merchant, Brenda Bruce, Esmond Knight, and Godfrey Quigley.