The air was suddenly supercharged with dynamic tension. The keen dagger-point hovered high above me--loud and clear sounded the skirl of a police whistle and on the heels of the sound there came a terrific crash from the front of the warehouse! Kathulos leaped into frenzied activity. Hissing orders like a cat spitting, he sprang for the hidden door and the rest followed him. Things happened with the speed of a nightmare. Li Kung had followed the rest, but Kathulos flung a command over his shoulder and the Chinaman turned back and came rushing toward the altar where I lay, dagger high, desperation in his countenance. [Illustration: "Kathulos leaped into frenzied activity, hissing orders like a cat."] A scream broke through the clamor and as I twisted desperately about to avoid the descending dagger, I caught a glimpse of Kathulos dragging Zuleika away. Then with a frenzied wrench I toppled from the altar just as Li Kung's dagger, grazing my breast, sank inches deep into the dark-stained surface and quivered there. I had fallen on the side next to the wall and what was taking place in the room I could not see, but it seemed as if far away I could hear men screaming faintly and hideously. Then Li Kung wrenched his blade free and sprang, tigerishly, around the end of the altar. Simultaneously a revolver cracked from the doorway--the Chinaman spun clear around, the dagger flying from his hand--he slumped to the floor. Gordon came running from the doorway where a few moments earlier Zuleika had stood, his pistol still smoking in his hand. At his heels were three rangy, clean-cut men in plain clothes. He cut my bonds and dragged me upright. "Quick! Where have they gone?" The room was empty of life save for myself, Gordon and his men, though two dead men lay on the floor. I found the secret door and after a few seconds' search located the lever which opened it. Revolvers drawn, the men grouped about me and peered nervously into the dark stairway. Not a sound came up from the total darkness. "This is uncanny!" muttered Gordon. "I suppose the Master and his servants went this way when they left the building--as they are certainly not here now!--and Leary and his men should have stopped them either in the tunnel itself or in the rear room of Yun Shatu's. At any rate, in either event they should have communicated with us by this time." "Look out, sir!" one of the men exclaimed suddenly, and Gordon, with an ejaculation, struck out with his pistol barrel and crushed the life from a huge snake which had crawled silently up the steps from the blackness beneath. "Let us see into this matter," said he, straightening.