"You seem to have changed your mind about the matter," said Laurance drily, "for when my letter appeared you were assured that there was such a gang." "Only because of Sir Charles's remarks to Durwin." "It was a pity Sir Charles was not more explicit," retorted Freddy crossly. "He had no time to be explicit," said Dan patiently, "since he died before he explained. But let us admit, for the sake of argument, that such a gang exists. Why should the members murder poor people?" "Folks have been murdered by way of revenge, as well as for money. And let me remind you, Dan, that four or five of these victims mentioned in the letters had money, or were about to inherit money. I am quite convinced," said Laurance, striking the table, "that there is such an association." "An association for what?" "You are very dull. To get undesirable people out of the way. Remember, in the reign of Louis XIV there were dozens of poisoners in Paris who undertook to kill people when engaged to do so. The reason was for revenge, or desire for money, or--or--or for other reasons," ended Laurance vaguely. "Hum!" Dan stroked his chin, "it may be as you say. Certainly Sir Charles was got rid of, because he knew too much." "About this gang," insisted Laurance, "since he was to see Durwin about the same. I am certain that such an association exists." "You said that before," Halliday reminded him. "And I say it again. At all events there is one thing certain--that we have learned from these letters of many mysterious crimes." "But only in one case was the fly discovered," objected Dan again. "That is not to be wondered at," replied the journalist; "the wonder is that such a small insect should be noticed at all. No one would ever think of connecting a fly, whether dead or alive, with the death. The mother of this schoolmistress did not, until your experience with regard to Moon was quoted in my letter. The fly business is quite ridiculous." "And perhaps means nothing." "Oh, I think it does, seeing that in Moon's case, the fly was artificial. Probably in the case of the schoolmistress it was artificial also, only the mother who noticed it did not make an examination. Why should she? I wonder the gang don't have a better trade-mark." "Perhaps the gang may think it would be spotted if it did." "Then why have any trade-mark at all," answered Laurance, sensibly. "If there is to be a sign, there should be some sensible one. If the fly was stamped on the skin, as the purple fern was stamped, there would be some sense in the matter. But a fly, artificial or real, is----" Freddy spread out his hands, for words entirely failed him.