In the absence of Lefebre, who could have solved the enigma, and whom Caffarelli had not decided to arrest, there remained one way of discovering Mme. de Combray’s secret—­an odious way, it is true, but one that Licquet, in his bewilderment, did not hesitate to employ.  This was to put a spy with her, who would make her speak.  There was in the Conciergerie at Rouen a woman named Delaitre, who had been there for six years.  This woman was employed in the infirmary; she had good enough manners, expressed herself well, and was about the same age as Mme. Acquet.  It was easy to believe that, in return for some remission of her sentence, she would act as Licquet’s spy.  They spoke of her to the Marquise, taking care to represent her as a royalist, persecuted for her opinions.  The Marquise expressed a wish to see her; Delaitre played her part to perfection, saying that she had been educated with Mme. Acquet at the convent of the Nouvelles Catholique, and that she felt honoured in sharing the prison of the mother of her old school friend.  In short, that evening she was in a position to betray the Marquise’s confidence to Licquet.  She had learned that Mme. Acquet had assisted at many of the attacks on coaches, dressed as a man.  Mme. de Combray dreaded nothing more than to have her daughter fall into the hands of the police.  “If she is taken,” she said, “she will accuse me.”  The Marquise was resigned to her fate; she knew she was destined for the scaffold; “after all, the King and the Queen had perished on the guillotine, and she would die there also.”  However, she was anxious to know if she could be saved by paying a large sum; but not a word was said about the yellow horse.

The next day she again wrote of the fear she felt for her daughter; she would have liked to warn her to disguise herself and go as a servant ten or twelve leagues from Falaise.  “If she is arrested she will speak, and then I am lost,” she continued; so that Licquet came to the conclusion that the reason the Marquise did not want the yellow horse to be found was that it would lead to the discovery of her daughter.  Mme. Acquet had so successfully disappeared during the last two weeks that Real was convinced she had escaped to England.  Nothing could be done without d’Ache or Mme. Acquet.  The failure of the pursuit, showing the organised strength of the royalist party and the powerlessness of the government, would justify Caffarelli’s indolent neutrality.  On the other hand, Licquet knew that failure spelled ruin for him.  He had made the affair his business; his prefect, Savoye-Rollin, was very half-hearted about it, and quite ready to stop all proceedings at the slightest hitch.  Real was even preparing to sacrifice his subordinate if need be, and to the amiable letters at first received from the ministry of police, succeeded curt orders that implied disfavour.  “It is indispensable to find Mme. Acquet’s retreat.”  “You must arrest d’Ache without delay, and above all find the yellow horse.”