When ambitious Oliver Cromwell (Alan Howard) overthrows the king, Cardinal Mazarin (Philippe Noiret) enlists a down-and-out D'Artagnan (Michael York) to rally the Musketeers against him. Porthos (Frank Finlay) accepts at once, but Athos (Oliver Reed) and Aramis (Richard Chamberlain) are reluctant. Still, the three reunite, but they are soon torn apart by infighting. They get a chance at redemption when they are sent to England to save the life of King Charles I (Bill Paterson).