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.

The Four Musketeers defend the queen and her dressmaker from Cardinal Richelieu and Milady de Winter.

It's 1649: Mazarin hires the impoverished D'Artagnan to find the other musketeers: Cromwell has overthrown the English king, so Mazarin fears revolt, particularly from the popular Beaufort. Porthos, bored with riches and wanting a title, signs on, but Aramis, an abbé, and Athos, a brawler raising an intellectual son, assist Beaufort in secret. When they fail to halt Beaufort's escape from prison, the musketeers are expendable, and Mazarin sends them to London to rescue Charles I. They are also pursued by Justine, the avenging daughter of Milady de Winter, their enemy 20 years ago. They must escape England, avoid Justine, serve the Queen, and secure Beauford's political reforms.