In Chapter 13, we find out that Constance Bonacieux is only twenty-three years old; since she is married to a fifty-one-year-old stingy, selfish husband, she would naturally make a likely candidate for a love affair with d'Artagnan, especially since we also learn that her husband thinks of his love for his wife as being secondary to his love for money and influence. Bonacieux is thus an easy prey for the powerful cardinal, and he quickly becomes the cardinal's dupe. Later, when Constance asks him to do a service for the queen, he will not consent to it; thus, she turns to our hero, d'Artagnan, and asks him to perform this crucial deed for the queen.
In his questioning of Monsieur Bonacieux, the cardinal is seen to have an acute sense of the intrigues of the court. He knows that the duke of Buckingham is in Paris, and he is able to discover where both the duke and Madame de Chevreuse are staying — that is, in the houses that Constance Bonacieux often visited, pretending to her husband that she was visiting "tradesmen." Through his spies, the cardinal is able to deduce that the queen gave Buckingham the rosewood box containing the diamond tags. Knowing this, he requests the king to give a ball and demand that the queen wear the diamond tags. This demand, as we soon will see, will require d'Artagnan to go on his first adventure. He will have to get the diamond tags and return them to the queen before the date of the ball, a date which the cardinal sets as soon has he hears that his spy, Milady, has stolen two of the diamond tags — snipped them off while she was dancing with Buckingham.
In an earlier chapter, when d'Artagnan helped get a message to Monsieur de La Porte, the gentleman told d'Artagnan to find someone with a slow clock who could provide him with an alibi. D'Artagnan went to see Treville and reset his clock; now, when Treville has to give his word of honor that d'Artagnan was with him at a precise hour, he can do so — fully believing that he is telling the truth. Consequently, d'Artagnan is freed from all accusations by the cardinal.
