Man in the Iron Mask, Paperback/Alexandre Dumas

In the Musketeers’ final adventure, D’Artagnan remains in the service of the corrupt King Louis XIV after the Three Musketeers have retired and gone their separate ways. Meanwhile, a mysterious prisoner in an iron mask wastes away deep inside the Bastille. When the destinies of king and prisoner converge, the Three Musketeers and D’Artagnan find themselves caught between conflicting loyalties.