Here, as part of the novel of intrigue, we are introduced to the villainous "authorities" who set a trap and arrest anyone — innocent or guilty — who enters the "mousetrap." In modern terms, this is similar to police entrapment, a technique whereby the police use an officer to trap someone into violating a law so that the police can arrest that person. It is by this method that d'Artagnan meets Constance Bonacieux, who becomes his first love.
Constance Bonacieux's escape from her captors (by tying sheets together and letting herself down from a window) and d'Artagnan's rescue of her are in the best swashbuckling, romantic tradition, as is the scene where the four guards battle against d'Artagnan and d'Artagnan overcomes these odds and rescues the fair damsel in distress.
Also in the tradition of the troubadors and other devoted cavaliers who love for-the-sake-of-love, d'Artagnan immediately falls in love with Constance Bonacieux; she will be d'Artagnan's beloved for whom he will perform valorous deeds. His relationship with Constance Bonacieux will, of course, eventually cause him to volunteer to perform a great service for the queen, thereby saving her honor and virtue. Ultimately, then, d'Artagnan's love and devotion to Constance Bonacieux will be one of the causes for his own advancement in society and will tightly entangle him in the deadly political intrigues of France. In other words, the relationship established here and intensified when d'Artagnan helps Constance Bonacieux slip the duke of Buckingham into the Louvre are sufficient for Constance to trust d'Artagnan to go on the dangerous and highly secret mission for the queen.
The importance of this love affair is a commentary on the times. Dumas writes that Constance Bonacieux was an amorous ideal, that she knew the secrets of the court and was not insensitive to masculine attentions, even though she was married. Furthermore, it was the custom of the time for a young and handsome man to take money or other gifts from his mistress, and the young and handsome d'Artagnan is always in need of money.
