The Inspector essayed a feeble smile. “Just—a—little tired, son, I guess,” he grunted. “I just heard from our housebreaker....” “And—?” “He found absolutely nothing.” Ellery gripped his father’s arm and led him to the chair by the bed. The old man slumped into it, his eyes ineffably weary. “Ellery, old son,” he said, “the last shred of evidence is gone. It’s maddening! Not a morsel of physical, tangible evidence that would convict the murderer in court. What have we? A series of perfectly sound deductions—and that’s all. A good lawyer would make Swiss cheese out of our case.... Well! The last word hasn’t been spoken yet,” he added with a sudden grimness as he rose from the chair. He pounded Ellery’s broad back in returning vigor. “Get to bed, son,” he said. “You’ve got to get up early to-morrow morning. I’m going to sit up and think.” INTERLUDE IN WHICH THE READER’S ATTENTION IS RESPECTFULLY REQUESTED The current vogue in detective literature is all for the practice of placing the reader in the position of chief sleuth. I have prevailed upon Mr. Ellery Queen to permit at this point in The Roman Hat Mystery the interpolation of a challenge to the reader.... “Who killed Monte Field?” “How was the murder accomplished?” ... Mr. Queen agrees with me that the alert student of mystery tales, now being in possession of all the pertinent facts, should at this stage of the story have reached definite conclusions on the questions propounded. The solution—or enough of it to point unerringly to the guilty character—may be reached by a series of logical deductions and psychological observations.... In closing my last personal appearance in the tale let me admonish the reader with a variation of the phrase _Caveat Emptor_: “Let the reader beware!” J. J. McC. PART FOUR _“The perfect criminal is a superman. He must be meticulous in his technique: unseen, unseeable, a Lone Wolf. He must have neither friends nor dependents. He must be careful to a fault, quick, of brain, hand and foot.... But these are nothing. There have been such men.... On the other hand, he must be a favored child of Fate—for circumstances over which he cannot have the remotest control must never contrive his downfall. This, I think, is more difficult to achieve.... But the last is most difficult of all. He must never repeat his crime, his weapon or his motive! ... In all my twoscore years as an official of the American police I have not once encountered the perfect criminal nor investigated the perfect crime.”_ —_From_ American Crime and Methods of Detection, _By_ Richard Queen. CHAPTER XIX IN WHICH INSPECTOR QUEEN CONDUCTS MORE LEGAL CONVERSATIONS