"Yes, you fail, all right," interrupted Darrow. "You had all the strings in your hands, but you were a mile behind me in the solution of this mystery. I'll tell you why: it was for the same reason that you're going to fail a second time, now that once again I've put all the strings in your hands." "I must confess I fail to gather your meaning," said Professor Eldridge coldly. "It was for the same reason that always until his death you were inferior to dear old Doctor Schermerhorn as a scientist. You are an almost perfect thinking machine." Darrow quite deliberately lighted a cigarette, flipped the match into the grate, and leaned back luxuriously. Professor Eldridge sat bolt upright, waiting. Helen Warford watched them both. "You have no humanity; you have no imagination," stated Darrow at last. "You follow the dictates of rigid science, and of logic." "Most certainly," Eldridge agreed to this, as to a compliment. "It takes you far," continued Darrow, "but not far enough. You observe only facts; I also observe men. You will follow only where your facts lead; I am willing to take a leap in the dark. I'll have all this matter hunted out while you are proving your first steps." "That, I understand it, is a challenge?" demanded Eldridge, touched in his pride of the scientific diagnostician. "That," said Percy Darrow blandly, "is a statement of fact." "We shall see." "Sure!" agreed Darrow. "Now, the thing to do is to find Monsieur X. I don't know whether your curiously scutellate mind has arrived at the point where it is willing to admit the existence of Monsieur X or not; but it will. The man who finds Monsieur X wins. Now, you know or can read in the morning paper every fact I have. Go to it!" Eldridge bowed formally. "There's one other thing," went on Darrow in a more serious tone of voice. "You have, of course, considered the logical result of this power carried to its ultimate possibility." "Certainly," replied Eldridge coldly. "The question is superfluous." "It is a conclusion which many scientific minds will come to, but which will escape the general public unless the surmise is published. For the present I suggest that we use our influence to keep it out of the prints." Eldridge reflected. "You are quite right," said he; and rose to go. After his departure Helen turned on Darrow. "You were positively insulting!" she cried, "and in my house! How could you?" "Helen," said Darrow, facing her squarely, "I maintained rigidly all the outer forms of politeness. That is as far as I will go anywhere with that man. My statement to him is quite just; he has no humanity." "What do you mean? Why are you so bitter?" asked Helen, a little subdued in her anger by the young man's evident earnestness. "You never knew Doctor Schermerhorn, did you, Helen?" he asked. "The funny little old German? Indeed, I did! He was a dear!"