Once or twice, we listened. The spies were absolutely silent--well trained to that sort of nocturnal investigation, no doubt. As Ray and I got to the door of the big room, which, by the light of the flash-lamp used by the intruders, we could see was fitted with all sorts of appliances, we witnessed through the crack that they had secured a number of specimens of metals and were all three at that moment engaged in drilling a hole in the big dark green safe standing in the corner. "Now," whispered the constable, "let's rush them." And with a loud shout we dashed in upon them, revolvers in hand. In an instant we were in total darkness. Deep curses in Italian sounded, and I heard a desperate struggle taking place. Somebody grabbed at me, but it was our friend the constable. Then, by the red flash of a revolver which somebody fired, I distinguished the flying form of one of the intruders through the doorway. Next second, in the darkness, I felt a man brush past me, and instantly I closed with him. We fell together, and as I gripped the fellow's throat he ejaculated a loud imprecation in Italian. Then we rolled over in desperate embrace, but as I forced him beneath me, shouting to the constable, whose lantern had been knocked from his hand and broken, I suddenly felt a crushing blow upon the skull. I saw a thousand stars, and then the blackness of unconsciousness fell upon me. * * * * * When I again grew cognisant of what was going on about me, I found myself lying in bed in the Richmond Cottage Hospital with a pleasant-faced nurse bending eagerly over me. It was still night, for the gas was burning. She asked how I felt, remarking that I had received a nasty crack, and had lain there unconscious for three whole days. Presently I felt the presence of some one else near me, and gradually made them out to be Ray and Vera. At first they would tell me nothing, but after the doctor had seen me, Ray in his cheery way said: "Yours was a bit of hard luck, old fellow. The blackguards all got away--all three of them. But we were just in time, for in that safe were the memoranda of the Professor's experiments which, together with the specimens of the new metal that could have been analysed, would have undoubtedly placed the secret of the new steel in the hands of the German Admiralty!" "Then we really prevented them?" I said eagerly, feeling the bandages about my head. "Just in the very nick of time, old man," he replied. "And we did more. We managed to save Miss Nella." "How?" I inquired eagerly. "She's here. She'll tell you herself." And next moment I saw her standing before me with the Professor.