It is May and the fate of nations is at stake. Mazarin plots, Louis XIV is in love, and Raoul de Bragelonne, son of Athos, is intent on serving France and winning the heart of Louise de la Valliére. D'Artagnan, meanwhile, is perplexed by a misterious stranger, and soon he learns that his old comrades already have a great project in hands. Athos seeks the restoration of Charles II, while Aramis, with Porthois in tow, has a secret plan involving a masked prisioner and the fortification of the island of Belle-Île. D'Artagnan finds a thread leading him to the French court, the banks of the Tyne, the beaches of Holland, and the dunes of Brittany.