England, early 18th century. The close relationship between Queen Anne and Sarah Churchill is threatened by the arrival of Sarah's cousin, Abigail Hill, resulting in a bitter rivalry between the two cousins to be the Queen's favourite.

The young D'Artagnan arrives in Paris with dreams of becoming a King's musketeer. He meets and quarrels with three men, Athos, Porthos, and Aramis, each of whom challenges him to a duel. D'Artagnan finds out they are musketeers and is invited to join them in their efforts to oppose Cardinal Richelieu, who wishes to increase his already considerable power over the King. D'Artagnan must also juggle affairs with the charming Constance Bonancieux and the passionate Lady De Winter, a secret agent for the Cardinal.