Dorrington smiled the smile of a sphinx. "M. Bouvier," he said, "it is my trade to know everything--everything." He put the pen down and gazed whimsically at the other. "My agents are everywhere. You talk of the secret agent of the Russian police--they are nothing. It is my trade to know all things. For instance"--Dorrington unlocked a drawer and produced a book (it was but an office diary), and, turning its pages, went on. "Let me see--B. It is my trade, for instance, to know about the Café des Bons Camarades, established by the late Madame Bouvier, now unhappily deceased. It is my trade to know of Madame Bouvier at Bonneuil, where the charcoal was burnt, and where Madame Bouvier was unfortunately left a widow at the time of the siege of Paris, because of some lamentable misunderstanding of her husband's with a file of Prussian soldiers by an orchard wall. It is my trade, moreover, to know something of the sad death of that husband's brother--in a pit--and of the later death of his widow. Oh yes. More" (turning a page attentively, as though following detailed notes), "it is my trade to know of a little quarrel between those brothers--it might even have been about a diamond, just such a diamond as you have come about to-night--and of jewels missed from the Tuileries in the great Revolution a hundred years ago." He shut the book with a bang and returned it to its place. "And there are other things--too many to talk about," he said, crossing his legs and smiling calmly at the Frenchman. During this long pretence at reading, Bouvier had slid farther and farther forward on his chair, till he sat on the edge, his eyes staring wide, and his chin dropped. He had been pale when he arrived, but now he was of a leaden gray. He said not a word. Dorrington laughed lightly. "Come," he said, "I see you are astonished. Very likely. Very few of the people and families whose _dossiers_ we have here" (he waved his hand generally about the room) "are aware of what we know. But we don't make a song of it, I assure you, unless it is for the benefit of clients. A client's affairs are sacred, of course, and our resources are at his disposal. Do I understand that you become a client?" Bouvier sat a little farther back on his chair and closed his mouth. "A--a--yes," he answered at length, with an effort, moistening his lips as he spoke. "That is why I come." "Ah, now we shall understand each other," Dorrington replied genially, opening an ink-pot and clearing his blotting-pad. "We're not connected with the police here, or anything of that sort, and except so far as we can help them we leave our client's affairs alone. You wish to be a client, and you wish me to recover your lost diamond. Very well, that is business. The first thing is the usual fee in advance--twenty guineas. Will you write a cheque?" Bouvier had recovered some of his self-possession, and he hesitated. "It is a large fee," he said.