Watch The Three Musketeers for Free: How to Stream the Movie Online at 123Movies. . 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.