Such was the problem I had to solve. And the key to it was just one bogus wedding card impregnated with the slowly dying odour of geranium. I cursed my luck as I reflected on the magnitude of the issues at stake and the paucity of the tools with which I had to work. For if "Captain James Easterbrook" was unknown in Chester, the home of his supposed bride, what was my chance of penetrating his disguise? Yet, somehow or other, we must succeed. That Cauvin was receiving money from England I was absolutely convinced, and I was determined to take this chance--the best we had had--of locating the real men behind the Hidden Hand in England. Next day I left Chester by a very early train for London. When we reached Rugby I bought a copy of _The Times_, and the first thing that caught my eye was a cryptically worded message at the head of the personal column. It conveyed to me the startling news that Madame Gabrielle had been recognised by some alien agent of whom she was highly suspicious, had left the Grosvenor Hotel in her alarm, and had returned to Paris! CHAPTER SEVEN. THE ELUSIVE VAN ROSEN. Evidently something very serious had happened. My first impulse was to hasten to the Grosvenor Hotel, engage a room there, and try to discover something of the cause which had brought about Madame Gabrielle's sudden flight. Perhaps my anxiety for her safety operated more powerfully than I ought to have allowed. In our business personalities are nothing; it is the end that counts. A moment's reflection showed me that in taking this course I should simply be playing into the enemy's hands. I was too well known. I hoped that my presence in England was not suspected by the German agents, and if I ventured to stay at the Grosvenor they would certainly very soon have me under close observation. By using the official telephone between London and Paris I managed to get into communication with Madame Gabrielle at her flat in the Boulevard Pereire, and soon learnt the reason for her flight. Van Rosen had discovered her, and was watching her closely. Here, indeed, was an antagonist worthy of my steel! I had long known-- and so far as his abilities went, had respected--van Rosen as one of the cleverest agents of the Koniggratzer-strasse. He was able to pose as an Englishman--a rare accomplishment in a German--for he had been educated at Haileybury, and had been in England off and on since his youth. He was now living in a north-western suburb, where he posed as Mr George Huggon-Rose, a solicitor who had retired from practice. Only British apathy made this possible. A moment's investigation would have shown that the man could not have been what he pretended, for no such retired solicitor as Mr George Huggon-Rose was known to the Law Society.