"I don't think so," he declared; "I haven't seen him anywhere in the hotel." "Seen him?" Sime turned his dull gaze upon the speaker. "How should you know him?" Cairn raised his hand to his forehead in an oddly helpless way. "No, of course not--it's very extraordinary." They took their seats at a small table, and in mutual silence loaded and lighted their pipes. Sime, in common with many young and enthusiastic medical men, had theories--theories of that revolutionary sort which only harsh experience can shatter. Secretly he was disposed to ascribe all the ills to which flesh is heir primarily to a disordered nervous system. It was evident that Cairn's mind persistently ran along a particular groove; something lay back of all this erratic talk; he had clearly invested the Mask of Set with a curious individuality. "I gather that you had a stiff bout of it in London?" Sime said suddenly. Cairn nodded. "Beastly stiff. There is a lot of sound reason in your nervous theory, Sime. It was touch and go with me for days, I am told; yet, pathologically, I was a hale man. That would seem to show how nerves can kill. Just a series of shocks--horrors--one piled upon another, did as much for me as influenza, pneumonia, and two or three other ailments together could have done." Sime shook his head wisely; this was in accordance with his ideas. "You know Antony Ferrara?" continued Cairn. "Well, he has done this for me. His damnable practices are worse than any disease. Sime, the man is a pestilence! Although the law cannot touch him, although no jury can convict him--he is a murderer. He controls--forces--" Sime was watching him intently. "It will give you some idea, Sime, of the pitch to which things had come, when I tell you that my father drove to Ferrara's rooms one night, with a loaded revolver in his pocket--" "For"--Sime hesitated--"for protection?" "No." Cairn leant forward across the table--"to shoot him, Sime, shoot him on sight, as one shoots a mad dog!" "Are you serious?" "As God is my witness, if Antony Ferrara had been in his rooms that night, my father would have killed him!" "It would have been a shocking scandal." "It would have been a martyrdom. The man who removes Antony Ferrara from the earth will be doing mankind a service worthy of the highest reward. He is unfit to live. Sometimes I cannot believe that he does live; I expect to wake up and find that he was a figure of a particularly evil dream." "This incident--the call at his rooms--occurred just before your illness?" "The thing which he had attempted that night was the last straw, Sime; it broke me down. From the time that he left Oxford, Antony Ferrara has pursued a deliberate course of crime, of crime so cunning, so unusual, and based upon such amazing and unholy knowledge that no breath of suspicion has touched him. Sime, you remember a girl I told you about at Oxford one evening, a girl who came to visit him?" Sime nodded slowly.