"Did you perfume the cards before you printed them?" I asked him carelessly. I had kept the most important question till the last. "Perfume them!" he snorted, glaring at me through his spectacles. "Why, of course not--we don't scent invitation cards to weddings!" I knew that well, but I was glad to get the fact verified. And now for Mr Easterbrook and the captain! I was in high spirits, for I felt that at length I was getting near the heart of the mystery. Going direct to Lancaster Gate, I soon found the Easterbrooks' house, a large, handsome building overlooking Hyde Park. A few local inquiries soon told me all I wanted to know, and shortly after I was conveying my news to Hecq over the Paris telephone. For once the phlegmatic little man was shaken out of his habitual reserve, and his voice, when he had heard my news, fairly trembled with excitement. At last we were at close grips with our mysterious foe. Next day, Madame Gabrielle, whom I sent for again, and Aubert were installed in rooms in an obscure house in Bayswater. I spent the evening with them, and together we evolved a plan of operations which, I confess, required considerable "bounce"--I do not like the expression "daring" when it has to be applied to one's self. By this time I had cut myself adrift from our excellent colleagues of the Special Branch, fearing lest van Rosen and his friends might get on my track. So far, apparently, he had not located me, for, though I kept the sharpest possible look out, assisted by a clever detective who habitually assumed different disguises for the purpose, I could find no evidence whatever that I was being "shadowed." Madame Gabrielle, Aubert, and myself were also working apart, though I was directing the general plan of operations. Following up the trail I had struck in the Uxbridge Road, I soon secured some astounding facts regarding Mr Essendine Easterbrook, of Lancaster Gate. He was actually a native of Frankfort, who, after a brief but amazingly successful career in the City as a promoter of rubber companies, had amassed a big fortune and retired from the game of finance. He had become naturalised in 1909, and, profiting by the Briton's amazing indulgence to aliens of every kind, had changed his name from Essendine Wilhelm Estbruck to Essendine William Easterbrook. Very few people, I found out, had any idea of his real origin and of his German parentage and nationality. Now Mr "Easterbrook" had no son. He had, however, an English wife, and his wealth had won for them a position in London Society. They had frequently, before the war, entertained at their handsome house the wily director of propaganda, von Kuhlmann, who was then living in London, and also a certain Max Garlick. But, try as I would, I completely failed to establish any sort of connection between the Easterbrooks and Mr Huggon-Rose.