When the cardinal, through his extended and vast network of spies (one of whom is among the queen's ladies-in-waiting) discovers that the queen has given Buckingham the diamond tags, he asks the king to give a fabulous ball and demand that the queen wear the king's gift to her: the twelve diamond tags.
The queen is terrified when she learns about the ball and hears her husband order her to wear the diamond tags. She knows very well that they are in London, in the possession of the duke of Buckingham. Meanwhile, the cardinal sends one of his spies — the elegant and beautiful Milady — to London; he instructs her to dance with the duke, snip off at least two of the diamond tags, and return them to the cardinal so that he can use them in a blackmail scheme.
Ready to help the queen regain the diamond tags, whatever the cost, Constance Bonacieux pleads with d'Artagnan to undertake the dangerous trip to London in order to retrieve the diamond tags from the duke before the ball and thereby save the queen's reputation. D'Artagnan readily accepts Constance's request, and accompanied by the three musketeers, he begins the hazardous trip to London. On the way, they are continually ambushed by the cardinal's spies, and one by one, the musketeers are foiled from accompanying d'Artagnan to London.
When d'Artagnan reaches London, he reports the situation to Buckingham, who discovers in horror that two of the tags are missing. Immediately, he calls in his personal jeweler and instructs him to work furiously in order to make exact copies. He gives the copies to d'Artagnan, along with the remaining ten tags, and a superb, prearranged series of horses that will take d'Artagnan from London to Paris in twelve hours. Thus, the queen is able to appear in what seems to be all twelve of the diamond tags — to the utter astonishment of the cardinal. For d'Artagnan's heroic efforts, the queen secretly presents him with a large, magnificent diamond ring.
After agreeing to a rendezvous with Constance (which never takes place because she is again abducted by the cardinal's men), d'Artagnan is told that it is dangerous to remain in Paris: the cardinal knows everything that happens in Paris; it will not be long, before he learns about d'Artagnan's role in the diamond tag escapade. D'Artagnan therefore decides that this would be a good time to discover what happened to his musketeer friends.
