The young Gascon D'Artagnan arrives in Paris, his heart set on joining the king's Musketeers. He is taken under the wings of three of the most respected and feared Musketeers, Porthos, Aramis, and Athos. Together they fight to save France and the honor of a lady from the machinations of the powerful Cardinal Richelieu.

Cardinal Richelieu, engaged in intrigue at the court of Louis XIII, attempts to rule by threatening the queen, who is secretly in love with the Duke of Buckingham. From Gascony comes D'Artagnan to join the King's Musketeers in his quest for adventure. He wins the right to membership by proving his prowess with the sword and forms an eternal alliance with Athos, Porthos, and Aramis, the Three Musketeers. After many adventures, he embarks on a dangerous mission to England to recover a diamond brooch, a gift of the king, which the queen has given to Buckingham as a token of affection. He recovers it and returns in time to save the queen from the wrath of Louis, defeat the cardinal's intrigue, and win Constance, the queen's seamstress.