"I am not now dealing with facts, but with conjecture;" went on Dawson, after begging her pardon. "I have nothing to go upon, but the Germans have far more of imagination and ingenuity than we always credit to them. They must see that with the great advance in the Flying Corps of the Allied armies, and the opportunities which flying men have for collecting and conveying information, one flying spy would be worth a hundred spies on foot. For them to perceive is to act. I therefore conclude positively that they have agents in the flying squadrons of France and Belgium, and possibly even in our own. So I told the C. in C., and he agreed with me. He was good enough to say that he would never have thought of this had I not suggested it to him. Soldiers are not detectives, madame, and very few detectives are William Dawsons. If the War Office knew its business, every Assistant Provost-Marshal would be, not a soldier, but a man from the Yard, and I should be the P.M. in Chief on the Headquarters Staff. I should wear a general's uniform and hat." "You would look sweet," said Madame politely. Dawson, the ex-private of Red Marines, swelled out his chest and felt himself to be a Major-General at the least. "They will do their best to follow up my idea at the Front, and I shall start a campaign here. For I become more and more convinced that the head centre of the German secret service is here in London. Paris, even before the war, was too watchful, and now is as hot as Hell. London reeked with spies, and though we locked up the worst of them when war broke out, lots still remain. If you only knew how many we laid by the heels and keep shut up without any trial, or nonsense of that sort, you would be surprised. It is only since the Defence of the Realm Act was passed that England has become a free country. We keep a drag-net going continually, we have hundreds of agents in all suspected quarters, but this wilderness of bricks and mortar is too big even for us. Once an enemy agent has got himself into an English or Allied uniform, he is horribly difficult to run down. That is where you, and those like you, come in. Are you sure, my dear madame, that you can pass without detection as a Frenchwoman or a French-Belgian?" Madame Gilbert put up her left hand, and began to tick off her qualifications. "My father was a Swede, my mother was Irish, I was educated in France from the age of three to eighteen, I married an Italian. Brussels I know almost as well as dear Paris. I can be Parisienne or Bruxelloise--whichever you wish, Mr. Dawson."