"Ah! my friend. I see you have mastered the essentials," said Hecq approvingly. "Now Cauvin and all his friends are under the strictest surveillance; the question is how we are to secure evidence to convict him of the espionage he is undoubtedly concerned in. We can arrest him, of course, at any moment; he has no chance whatever of getting away. Every letter he sends or receives is opened and photographed, yet, up to the present, he has been too clever for us. If he were put on trial for espionage to-morrow, not even his friendship with Miassoyedeff would prevent him from being acquitted. We have no evidence against him whatever, beyond the fact of his sudden wealth, and that, even in these times, is not enough." And Hecq looked at me with an appeal in those soft, strange eyes of his. I could see that the case of Cauvin presented itself to him as supremely important, and that it must be solved if we were ever to grapple successfully with the mysterious, deadly influence whose workings we could feel and trace all around us, but the real wielder of which appeared constantly to slip through our fingers. "I quite understand you," I said, sipping the little glass of Cointreau he had offered me. "There is only one thing to be done. We must find that finger of the Hidden Hand in England." "Exactly, my dear Sant," exclaimed my chief, with a quick gesture of approval. "We seem to be losing ground day by day. Why? At all costs the position must be retrieved. You will want Madame Soyez to help you. Let me see; she is at present in England. I sent her across only a week ago to make some inquiries. Excuse me a moment while I speak to Guillet," and he left me to go to the telephone. Monsieur Guillet was his private secretary, who controlled his "financial office" in the Boulevard des Capucines. A few minutes later he returned, saying: "Madame is to-day at the Midland Grand Hotel in Manchester. Presuming that you wish to meet her, I have told Guillet to telegraph, asking her, if possible, to meet you to-morrow night in London." "No," I said at once. "That won't do. We cannot begin to work in England yet. I must learn a lot more about this interesting person Cauvin, who has so mysteriously acquired a fortune. Then we will begin to probe matters across the Channel. Recall Madame Gabrielle here and we will set to work. But it will be extremely difficult. The investigation of the Hidden Hand in England has always met with failure, so far as the principals are concerned. We have caught one or two of the minor tools, but the master-mind has always eluded us, although the British Secret Service is most excellent." "Ah, _mon cher_ Sant, there I agree most cordially with you. The world little dreams of the astuteness and resourcefulness of our colleagues at Whitehall. One day it will know--and it will be greatly surprised. Very well, I will order Madame Gabrielle to come direct to Paris."