The mysterious secret possessed by the woman I adored, the woman who held me under the spell of her marvellous beauty, was of a tragic and terrible nature, I felt assured. No doubt it had some connection with Dudley's death, and that sinister circumstance, once elucidated, would, I knew, furnish a very valuable clue to the identity of the spy, if perchance the innocence of my companion should be established, as I hoped it might be. There was still one fact, too, that required explanation, one that seemed to prove conclusively that Dudley was in the pay of our enemies. I had found, on looking over his possessions in our cottage at Shepperton, some pieces of crumpled foolscap. He had evidently intended to throw them away, but being unable to get rid of them at the moment, had placed them in a drawer and locked them up. On smoothing them out, I found another piece of paper inside. To my astonishment I saw it was a letter written by me, while the pieces of foolscap accompanying it were covered with words and sentences in ink and pencil, showing how carefully he had studied and copied all the characteristics of my handwriting. These papers were, in themselves, sufficient evidence that he had practised the forger's art. I had, after leaving Staines, returned straight to Shepperton, and in company with a detective carefully investigated all my friend's belongings. We spent the afternoon and evening in reading through heaps of letters, but discovered nothing that would lead to any suspicion of foul play. The detective made notes of one or two of the addresses of the writers, and took charge of several letters relating to money matters. When, however, we had removed all the correspondence from the small wooden box in which it had been kept, the detective ascertained that there was a false bottom, and unable to find out the secret whereby it might be opened, we forced it with a chisel. At first we were disappointed, only one insignificant-looking paper being therein concealed, but when the officer eagerly opened it I at once recognised its extreme importance, although I preserved silence. The paper was nothing less than a Russian passport of a special character signed by the Chief of Secret Police in St Petersburg, and countersigned by the Minister of the Interior himself. It was not a formally printed document, but written in Russian upon official paper stamped with the double-headed eagle. It was made out in the name of Dudley Ogle, and after explaining that he was an official engaged on secret service, gave him complete immunity from arrest within the Russian Empire. "What's this, I wonder?" the detective said, puzzled by the unfamiliar characters in the writing. Taking it from him I glanced through it, and without betraying the slightest surprise, answered, "Merely a passport for Russia."