In 17th century France, young D'Artagnan wants to join the King's Musketeers, but instead befriends three legendary musketeers—Athos, Porthos, and Aramis—and together, they become embroiled in the political intrigue surrounding King Louis XIII and his adversaries, particularly the powerful Cardinal Richelieu.

King Louis XIII of France is thrilled to have born to him a son - an heir to the throne. But when the queen delivers a twin, Cardinal Richelieu sees the second son as a potential for revolution, and has him sent off to Spain to be raised in secret to ensure a peaceful future for France. Alas, keeping the secret means sending Constance, lover of D'Artagnan, off to a convent. D'Artagnan hears of this and rallies the Musketeers in a bid to rescue her. Unfortunately, Richelieu out-smarts the Musketeers and banishes them forever.