D'Artagnan and his three friends volunteer to travel to Britain to retrieve the jewels, but along the way, they are ambushed by Richelieu's men. One by one, the Musketeers are forced to stay behind to hold off their pursuers. Finally, only d'Artagnan and his servant Planchet (Keenan Wynn) are left to reach the Duke. However, Richelieu had already sent the beautiful Milady, Countess de Winter (Lana Turner) to work her wiles on His Grace and steal two of the studs. The Duke's jeweler is able to make replacements quickly and d'Artagnan races back to France. He arrives just in time to save the Queen from disgrace.