Rouletabille here paused to take breath. I now understood what had appeared so unexplainable in the demeanour of Monsieur Robert Darzac towards my friend, and the facility with which the young reporter had been able to instal himself on the scene of the crime. My curiosity could not fail to be excited by all I had heard. I asked Rouletabille to satisfy it still further. What had happened at the Glandier during the past week?—Had he not told me that there were surface indications against Monsieur Darzac much more terrible than that of the cane found by Larsan? “Everything seems to be pointing against him,” replied my friend, “and the situation is becoming exceedingly grave. Monsieur Darzac appears not to mind it much; but in that he is wrong. I was interested only in the health of Mademoiselle Stangerson, which was daily improving, when something occurred that is even more mysterious than—than the mystery of The Yellow Room!” “Impossible!” I cried, “What could be more mysterious than _that_?” “Let us first go back to Monsieur Robert Darzac,” said Rouletabille, calming me. “I have said that everything seems to be pointing against him. The marks of the neat boots found by Frédéric Larsan appear to be really the footprints of Mademoiselle Stangerson’s fiancé. The marks made by the bicycle may have been made by _his_ bicycle. He had usually left it at the château; why did he take it to Paris on that particular occasion? Was it because he was not going to return again to the château? Was it because, owing to the breaking off of his marriage, his relations with the Stangersons were to cease? All who are interested in the matter affirm that those relations were to continue unchanged. “Frédéric Larsan, however, believes that all intercourse was at an end. From the day when Monsieur Darzac accompanied Mademoiselle Stangerson to the Grands Magasins de la Louvre until the day after the crime, he had not been at the Glandier. Remember that Mademoiselle Stangerson lost her reticule containing the key with the brass head while she was in his company. From that day to the evening at the Élysée, the Sorbonne professor and Mademoiselle Stangerson did not see one another; but they may have written to each other. Mademoiselle Stangerson went to the Post Office to get a letter, which Larsan says was written by Robert Darzac; for knowing nothing of what had passed at the Élysée, Larsan believes that it was Monsieur Darzac himself who stole the reticule with the key, with the design of forcing her consent, by getting possession of the precious papers of her father—papers which he would have restored to him on condition that the marriage engagement was to be fulfilled.