The formation of police forces naturally led to the invention of the "mousetrap," a tactic where authorities secretly occupy the home of an arrested suspect to ambush and detain anyone who subsequently visits. Cardinal Richelieuâs agents establish such a trap inside the apartment of the recently arrested M. Bonacieux. Since dâArtagnan lives on the floor above and utilizes a private alleyway, his residence remains exempt from these official searches. Meanwhile, the three musketeers search independently for information but discover nothing. Even Athos breaks his characteristic silence to question M. de TrĂ©ville, who only knows that the King is anxious, the Cardinal looks preoccupied, and the Queenâs red eyes betray heavy weeping. TrĂ©ville urges the companions to remain fiercely dedicated to serving the King and Queen. DâArtagnan transforms his own room into an observation post, removing his floorboards to peer through the exposed ceiling and spy on the interrogations happening directly below. The agents continuously question detainees about whether the Bonacieux couple passed along items or secrets, leading d'Artagnan to deduce that the Cardinal is desperately trying to confirm if the Duke of Buckingham is in Paris to see the Queen. The following evening at nine o'clock, a fresh visitor falls into the trap below. Hearing a woman resisting a violent search, d'Artagnan listens intently as the captive loudly identifies herself as Madame Bonacieux, a loyal servant to the Queen. Realizing she is being gagged and dragged away, d'Artagnan orders his valet, Planchet, to run and gather the musketeers. Impatient and determined, dâArtagnan leaps from his first-floor window into the street and forces his way into the landlord's apartment with his drawn sword. He easily defeats the four startled captors within ten minutes, sending them fleeing into the night in shredded clothes. DâArtagnan comforts the half-fainting Madame Bonacieux, a charming woman of twenty-five. He notices her drop a fine batiste handkerchief bearing the same crest that nearly sparked his duel with Aramis, and he discreetly slips it back into her pocket. Madame Bonacieux gratefully thanks her rescuer. D'Artagnan informs her that her innocent husband was sent to the Bastille due to a political conspiracy involving a scarred, swarthy kidnapper from Meung. She admits she escaped her own captivity by climbing out of a window using knotted bedsheets. Fearing the guards will return with reinforcements, they flee together to the Place Saint-Sulpice. To aid the Queen, she needs to contact her godfather, M. de La Porte, at the Louvre. D'Artagnan volunteers for the mission, swearing a gentleman's oath of absolute secrecy when she provides the secret password: "Tours and Brussels." He safely hides her in the vacant apartment of Athos on Rue FĂ©rou. D'Artagnan rushes to the Louvre, uses the password with the gatekeeper, Germain, and instructs the summoned La Porte to retrieve Madame Bonacieux. Before running off, La Porte prudently advises the young Gascon to establish an alibi for the evening. Taking this advice, d'Artagnan runs to M. de TrĂ©villeâs mansion. Slipping into TrĂ©ville's private cabinet, he alters the clock back by forty-five minutes. He then conducts a lengthy, composed discussion with his captain regarding his concerns for the Queen and Buckingham, matching TrĂ©villeâs own suspicions. After concluding the meeting at ten o'clock, dâArtagnan pretends he forgot his cane, returns to the empty cabinet, and successfully resets the clock to the correct time, securing a flawless alibi.