"I am attached to the Special Department at New Scotland Yard," explained the dark-bearded man. "Two months ago a member of the secret service in the employ of our Foreign Office made a report from Berlin that a young girl, named Gertie Drew, living in a Bloomsbury boarding-house, had approached the German military attaché offering, for three thousand pounds, to supply him with photographs of a number of confidential plans of our eastern counties and of the Clyde defences. The attaché had reported to the War Office in Berlin, hence the knowledge obtained by the British secret agent. The matter was at once placed in my hands, and since that time I have kept careful observation upon the girl—who has been a photographer's assistant—and those in association with her. The result is that I have fortunately managed to obtain possession of these negatives of your annotated plans."
"But how?" I demanded.
"By making a bold move," was the detective's reply. "The Germans were already bargaining for these negatives when I became convinced that the girl was only the tool of a man who had also been a photographer, and who had led a very adventurous life—an American living away in the country, near Colchester, under the name of Charles Sandford."
"Sandford!" I gasped, staring at him. "What is the girl like?"
"Here is her portrait," was the detective's reply.
Yes! It was the sweet face of my nightmare!
"What have you discovered regarding Sandford?" I asked presently, when I had related to the two men the story of the meeting at Salisbury and also my night's adventure.
"Though born in America and adopting an English name, his father was German, and we strongly suspect him of having, on several occasions, sold information to Germany. Yesterday, feeling quite certain of my ground, I went down into Essex with a search warrant and made an examination of the house. Upstairs I found a very complete photographic plant, and concealed beneath the floor-boards in the dining-room was a box containing these negatives, many of them being of your maps of the Clyde defences, which they were just about to dispose of. The man had got wind that we were keeping observation upon him, and had already fled. The gang consisted of an old hump-backed woman, who posed as his mother, a young woman, who he said was his married sister, but who was really the wife of his man-servant, and the girl Drew, who was his photographic assistant."
"Where's the girl? I suppose you don't intend to arrest her?"
"I think not. If you saw her perhaps you might induce her to tell you the truth. The plot to photograph those plans while you were insensible was certainly a cleverly contrived one, and it's equally certain that the two women you met in Salisbury only travelled with you in order to be convinced that you really carried the precious maps with you."