"Mr. Narkom, you have seen the method of administering the thing which caused the death of those five men; it is now only fair that you should know what that thing was," he said, turning to the superintendent. "It is known by two names--Devil's Dust and Dust of Death, and both suit it well. It is the fine, feathery powder that grows on the young shoots of the bamboo tree--a favourite method of secret killing with the natives of the Malay Peninsula and those of Madagascar, the Philippines and Ceylon. When blown into the nostrils of a living creature it produces first an awful agony of suffocation, a feeling as though the brain is coming down and exuding from the nostrils, then delirium, during which the victim invariably falls on his face and bites the earth; then comes death. Death without a trace, my friend, for the hellish dust all but evaporates, and the slight sediment that remains is carried out of the system by the spasm of enteric it produces. That is the riddle's solution. As for the rest, those men were lured here by letters--from Alvarez--telling them of the reef's great fortune, of the necessity for coming at once and bringing their deeds with them, and impressing upon them the possibility of being defrauded if they breathed one word to a mortal soul about their leaving or why. They came, they were invited to spend the night and to sleep upon that accursed bed, and--the devil's dust did the rest. I traced that out through poor Jim Peabody's sock. It was one of the blue yarn kind that are given to the inmates of workhouses. I traced him through that; and the others through the photographs. Each had been known to have received a letter from London, and each had in turn vanished without a word. Poor chaps! Poor unhappy chaps! Let us hope, dear friend, that they have found 'the Place of Sapphires' after all." CHAPTER V