Porthos and Aramis ride to the house of the Marquis to Belforde to meet Porthos' father. On the way, they run into two servant girls running from their master, Levesque. They are recaptured and imprisoned as thieves.
Constance mourns her husband and tells D'Artagnan that she needs time before she can consider being with him.
King Louis is still a recluse, refusing to participate in matters of state for fear of being assassinated. Rochefort essentially rules in his place. He convinces the Queen to send Constance away to grieve properly.
Belgard invites Porthos to dinner after confirming that he is in fact his father. He tells Porthos that he fell in love with married and they married in secret. His father did not approve though, and a few days after he found out both Marie and Porthos disappeared. He claims Treville helped sneak them away and left them in the slums.
Eleanor, Porthos' half sister and Levesque's wife, refuses to acknowledge Porthos. Levesque insults him, and Porthos ends up beating him in a duel.
Milady visits Rochefort and insinuates she knows he helped hire the Spanish assassin. He denies it, and orders her to find out if there is a romantic connection between Aramis and Anne.
Aramis finds one of the servant girls dead, and Eleanor lies about how she was killed.
Milady meets with Athos to try to sell her information about Rochefort. He tells her should reveal it for the sake of France.
At the palace, Monsieur Lemay proposes to Constance and tells her to take her time with her answer.
Aramis follows the second servant girl and watches her forced into a house in Paris. He takes the case to Treville, and they investigate. He finds out that Eleanor kidnaps girls and sells them to rich men in the city.
Porthos confronts Treville and quits the Musketeers when he admits it's all true. He returns to Belgard.
D'Artganan and Athos infiltrate Eleanor's auction and free the girls they have kidnapped.
Constance decides to end her mourning period and be with D'Artagnan.
Porthos finds another young girl locked inside Belgard's house, but Belgard claims to have no idea what Levesque was up to. He shoots Levesque, and Porthos chases him back into the house. Treville follow, and Porthos must choose which side he is on.
Porthos shoots Belgard, revealing that the picture Belgard had given him of his mother was a fake, which is when he knew Belgard was playing him.
Rochefort confronts Anne about Aramis and confesses his love for her. She rejects him, and he tries to rape her. Constance walks in and Anne manages to stab Rochefort in the eye. He calls for his guards and threatens to expose her.