"Now we are balked," he whispered. "This is more than a Chinese puzzle. Which door to choose?" "You may search me," replied Leggett. "What can be the object of all these doors?" "Stand back!" breathed Old King Brady, and he allowed the iron door which was self-closing to swing almost to. For out of one of the doors a man now came and that man was Dr. Garshaski. Hastily closing the door behind him he walked on rapidly along the corridor, opened another door and disappeared. Old King Brady carefully noted the door and was about to venture in, when the first door opened and two Chinamen emerged. Both were in American dress. One pointed along the corridor in the direction taken by the Doctor. They halted at the door through which Garshaski vanished. It was too far off to enable the watching detectives to see their faces plainly, the dim red lights making it additionally obscure. The two men stood talking for a few seconds then one of them got out what seemed to be a bunch of keys and began fumbling with the lock. As their backs were now turned to the detectives it was impossible to make out just exactly what they were doing. In a moment the door was opened and they disappeared inside. Old King Brady was about to press forward, but now came other delays. A different door opened and four Chinamen came out. They shuffled along the corridor, talking, and entered at still a different door. At the same time five others came out of that door and for fully ten minutes stood talking in the corridor, vanishing at last through the door out of which the others came. Again Old King Brady thought he had got his chance, but once more he was balked in the same way. At last his chance really did come and finding that they had the corridor to themselves he and Leggett pushed on. Now at the start the old detective had been at particular pains to identify that door. But did he still remember it? was the question. He could not feel by any means certain and the worst of it was a quick decision was absolutely necessary. "I think this is it," he said, pausing before a certain door. "You want to be sure," replied Leggett. "I am as sure as I can be. Yes. I think this is it." The door was locked and the old detective getting out his skeleton keys went at the job of opening it vigorously. He quickly succeeded. A narrow, dark staircase leading up lay beyond; leaving the door unlocked, Old King Brady pressed on to the top flight, no great distance, coming out upon a semi-circular platform where there were three doors. There was no light here. The old detective flashed his electric lantern around. "Your Chinese puzzle isn't it, Mr. Brady," whispered Leggett. "Is there any end to the mysteries with which these Chinks like to surround themselves?" "None, absolutely none," replied the old detective. "It makes one tired to try to follow their curves. But listen a moment. We may catch on to something."