Fighting breaks out between Britain and France. The Queen succeeds in freeing Constance and sends her to Buckingham for safety. When the war goes against him, Richelieu gives de Winter a carte blanche and sends her to Britain to assassinate his foe. The Musketeers learn of the plot and send Planchet to warn the Duke. Athos confronts Milady and recovers the carte blanche as proof of Richelieu's treachery. De Winter is imprisoned by the Duke and placed in the custody of Constance, but when the latter lets her guard down de Winter kills first her, then Buckingham. Athos and d'Artagnan arrive too late to save them.