Both he and Cecilia had risen, and we stood, I remember, just before the hearth, during this exchange. At this moment, a singular thing happened. The fire that had been sweeping in a broad wave-like curve into the chimney was checked suddenly. I had repeatedly marked the admirable draught, the facile grace of the flame as it rose and vanished. The cessation of the draught was unmarked by any of those premonitory symptoms by which a fire usually gives warning of evil intentions. The upward current of air had ceased utterly and without apparent cause. We were all aware of a choking, a gasping in the deep flue, which could not be accounted for by any natural stoppage incident to chimneys--the dislodging of masonry, or a packing of soot. The former was hardly possible and the house was not old enough to make the latter theory plausible. From my survey of the flue on my arrival in the afternoon, I judged that this particular chimney had been little used. The smoke now rolled out in billows and drove us back from the hearth. I seized the tongs and poker and began readjusting the logs, without, however, any hope of correcting a difficulty that lay patently in the upper regions of the flue itself. The smoke, after a courageous effort to rise, encountered an obstruction of some sort and ebbed back upon the hearth and out into the room. My efforts to stop the trouble by shifting the logs were futile, as I expected them to be, and I retreated quickly, making, I fear, no very gallant appearance as I mopped my face and eyes. [Illustration: I seized the tongs and poker and began readjusting the logs.] "Well," exclaimed Miss Hollister, who had rung for a servant to open the doors and windows, "this is certainly most extraordinary. What solution do you offer, Mr. Ames?" "The matter requires investigation. I can't venture an opinion until I have made a thorough investigation. The night is perfectly quiet and the wind is hardly responsible. I think we had better abandon the room until I can solve this riddle in the morning." The prompt opening of the windows and doors caused the slow dispersion of the smoke, but the lights in the room still shone dimly as through a fog. "It's beastly," ejaculated Wiggins, coughing. "I did n't suppose Pepperton would put a flue like that into a house. He ought to be shot." "It is fortunate," said Miss Hollister, "that Mr. Ames is on the ground. He now has a case that will test his most acute powers of diagnosis."