A sharp cry of pain--a man's cry--rang out from behind a closed door on the landing I was approaching. Then there followed a long-drawn-out groan, ending almost in a sigh. A tragedy was being enacted there! I clapped my hand upon the revolver I always carried in my hip-pocket, and went forward quickly, eager and puzzled, but just as I placed my feet upon the last steps to gain the landing where the man's chambers were, four or five of the stairs suddenly gave way beneath me, and I fell feet foremost into the great yawning opening there revealed. I was the victim of a dastardly treachery! I know that I clutched wildly at air when I felt myself falling down, down to what seemed an unfathomable depth. I held my breath, for at that instant a man's wild shriek rang in my ears. Then next second I felt my skull crushed, and with it all consciousness became blotted out. I was entrapped--helpless in the hands of quondam friends who were really my bitterest and most unscrupulous enemies. CHAPTER SEVENTEEN. IS EXTRAORDINARY. The agony was excruciating. A burning bubbling seethed in my brain, as though my skull were filled with molten metal. My mouth was parched, my neck stiff, and my jaws were fixed when I opened my eyes and found myself in a great chasm of cavernous darkness. How long I had lain there I have no idea. The thunder of rolling, roaring waters deafened me, and my lower limbs were so benumbed that at first I was unable to move them. I felt my leg, and then discovered the reason. Wet to the skin, I was lying half in water, my head alone being on some slightly higher ground--a fortunate circumstance that had certainly saved me from being drowned. Where was I? For fully ten minutes--minutes that seemed hours, I was utterly unable to move, but presently I managed, by dint of supreme effort, to struggle to my feet and grope about me unsteadily, at last finding a smooth arched wall. I lifted my hand above my head and found that I could touch the roof. In that pitch darkness, with the roaring torrent at my side, I dare not move two paces lest I might lose my foothold. I felt frantically in my pocket, and my heart leapt when I found that I still possessed a box of wax vestas. The silver box was water-tight. One of these I struck quickly, but its light was lost in that cavernous blackness. It only showed me the bricked walls, high to the roof, wet and slimy, and revealed to me that I was in one of the main sewers of London! At my side the great black torrent flowed on towards the outfall with deafening roar in that long, interminable tunnel beneath the Metropolis. Rats, hundreds of them, grey and scuttling, ran helter-skelter on seeing the fickle light; but I stood motionless leaning against the wall and gazing around at my weird surroundings until the match went out. My head reeled, I feared to walk lest I should stagger into the Stygian stream.