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 Königgrätzer-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.

As a matter of fact, it was through this very slip on his part that I had “spotted” van Rosen. We had suddenly lost sight of him a year or two before, and try as we would—for we knew that wherever he might be he would be dangerous—we could not locate him. The accident which led to his discovery was curious. I had been spending a few days in North London, and one morning stopped at the railway bookstall to buy a paper. As I approached the stall a tall, gentlemanly looking man, who had been chatting with the clerk, turned away and entered the train. Something about him struck me as strangely familiar.

“Who is that gentleman?” I asked the man at the stall.

“Oh,” he replied, “that’s Mr Huggon-Rose. He used to be a solicitor in the City, but he retired and has been living here for a year or two.”

But I was not quite satisfied; some odd memory, in which I felt sure Mr Huggon-Rose was concerned, haunted me all the way to town, and I could not shake it off. I had only seen van Rosen once, though I had had a good deal of experience, and it was not surprising that I failed to recognise him. When I got up to town I consulted the Law List, but could find no trace of Mr Huggon-Rose.

Then I became more suspicious, and before many days were over I had succeeded in definitely identifying Mr Huggon-Rose with one of the Kaiser’s cleverest spies. Thus the mystery of van Rosen’s disappearance was solved by his own slip. If, when I looked up the Law List, I had found Mr Huggon-Rose’s name and address duly set out, I should probably have thought I had been deceived by some chance resemblance and wasted no more time on the matter. How true it is that trifles make the sum of life!

The position now was plainly serious: van Rosen’s presence in London boded no good. The man was as unscrupulous as he was clever. The British contra-espionage department knew him well and had been greatly chagrined at losing sight of him. Afterwards, in consequence of my report to Hecq, he had been kept under close observation; but we had never been able to secure sufficient proof to justify his arrest, strong though our suspicions were. He had evidently been walking very warily since the outbreak of war. Unfortunately he had adopted that easiest of all cloaks of the German spy, and had become a naturalised Englishman just before war broke out. But the adage “Once a German always a German” applied with special force to van Rosen.

After speaking with Madame Gabrielle I had a long chat with Hecq over the private wire, and together we mapped out a pretty comprehensive plan of campaign, in which both Aubert and Madame Gabrielle had very definite parts to play.

Then the mysterious scented wedding card claimed my full attention, for I was determined to sift its secret to the bottom. First, I paid a visit to Somerset House, where I very thoroughly searched the records of recent marriages. These showed me that no marriage had taken place between persons named Wheatley and Easterbrook. A certain Agnes Wheatley had been born in June, 1894, at Mina Road, Old Kent Road, in the parish of St. George the Martyr, Southwark, and there were records of two James Easterbrooks. One was James Stanley Easterbrook, born in Lord Street, Southport, in 1881; the other, James Henry Charlton Easterbrook, had first seen the light of day in the village of Forteviot, Perthshire, in 1870. The Army List, of course, failed to show any Captain James Easterbrook, of the Royal Fusiliers.

All this did not carry me much farther. The father of the Southport Easterbrook was apparently a prosperous Blackburn tradesman; but that of the man born in Scotland was vaguely set down as of “no occupation,” a curious entry for a Scottish village, where practically everybody would be likely to live by the labour of his hands, and where one would hardly expect to find persons of leisured independence. The fact worried me. But an inquiry at Forteviot showed that there had been no Easterbrooks in the village for many years, and no one seemed to recollect anything about them.