The musketeers have retired, but when Aramis meets a prisoner in the Bastille and learns an incredible secret, he devises and enacts a plan that spurs Athos, Porthos, and D'Artagnan back into action. What is the future of France, and to whom are the musketeers loyal? The story begins in the Bastille, where a mysterious prisoner in an iron mask has been kept for eight years. He knows neither his name nor his crime, but after visiting him, Aramis discovers a secret so dangerous that it could topple the French throne. Aramis intends to free the prisoner and seize power, but the ripples of his actions reach further than he realizes. Formerly inseparable, the musketeers now find themselves on opposing sides of a power struggle, as Porthos aids Aramis, Athos focuses on his son, and D'Artagnan works for the dreaded Louis XIV. Where do their loyalties truly lie: with France, with each other, or with themselves?.