“The menservants sleep in the basement, the maids under the roof,” said Brujon, with a fat smile. He bade good-night to the new man and shuffled off to his office, whilst Lavenne retired to his room. Lavenne had a theory that every mind is like a safe in this particular: that the strongest safe can be picked if only the locksmith is clever enough. He knew that to get at a man’s secrets all questioning is useless, unless you bring your mind in tune with his. He knew that men run in tribes, and that there is a quite unconscious freemasonry between members of the same tribe. His instinct told him the tribe to which M. Brujon belonged, and his marvellous power of adaptability made him for the moment a member of the same tribe. In short, his scandalous stories about the unfortunate Madame Le Roux had put him at once _en rapport_ with the jovial, easy-going, scandal-loving and eminently Gallic mind of M. Brujon. That mind had opened without any difficulty to the skilful pick-lock, giving up the fact as to the situation of the room where his master busied himself with his strange chemistry. Lavenne had captured the situation of the room; it was now his business, and a much more difficult business, to capture the key, or, failing that, to pick the lock. He had brought with him an instrument similar to the old _crochet_ used by the burglars of France ever since the time of the Coquillards—the instrument that is used still under the name of the Nightingale. With this he could unlock and lock a door as easily as with a key. It remained to be seen whether the door of Camus’ room could be opened by this means. He blew out the candle, lay down on the bed, and closing his eyes began, as a pastime, to review the whole situation. It was a difficult situation enough. If Camus caught him in the act of making an examination of his room, Camus would certainly kill him, unless he killed Camus. Even in the latter event he would almost certainly be lost, unless he could make his escape, which was very unlikely. For if he killed Count Camus in his own house, he would, if caught, be most certainly hanged by de Sartines; it being the unwritten law of the Hôtel de Sartines that an agent caught on a business of this sort must never reveal his identity, or seek protection from the Law which employed him, suffering even death, if necessary, in the execution of his duty. But this consideration did not deflect our man a hair’s-breadth from the course he had mapped out for himself. The thing that was now occupying his mind was the room itself, of which he had caught a glimpse, its contents and its possible secrets.