Constance is kidnapped before D'Artagnan's eyes. In a frantic quest to save her, the young musketeer is forced to join forces with the mysterious Milady de Winter. But as war is declared and Athos, Porthos and Aramis have already joined the front, a terrible secret from the past shatters all old alliances. As the King falls further and further under the control of Cardinal Richelieu, D'Artagnan and the Musketeers are the last bastions before chaos. But, drawn into a plot that threatens to put the country to fire and sword, fate presents them with a terrible choice: will they have to sacrifice those they love to complete their mission?