"Probably nothing," Howells answered, "because, as I have said, success depends upon the courage of a man who kills in the dark while his victim sleeps. I simply give him the chance to attack me as he did Mr. Blackburn. Of course he realizes it would be a good deal to his advantage to have me out of the way. I ask him to come, therefore, as stealthily as he did last night. I beg him to match his skill with mine. I want him to play his miracle with the window or one of the locks. But I'll wager he hasn't the nerve, although I don't see why he should hesitate. He's a doomed man. I shall make my arrest in the morning. I shall publish all my evidence." Bobby wouldn't meet the narrow, menacing eyes, for he knew that Howells challenged him to a duel of slyness with the whole truth at stake. The detective's manner increased the hatred which had blazed in Bobby's mind when he had stood in the bedroom over his grandfather's body. For a moment he wished with all his heart that he might accept the challenge. He did the best he could. "I gather," he said, "that you haven't unearthed the motive for disturbing the body. And have you found the sharp instrument that caused death?" The detective answered tolerantly: "I have found a number of sharp instruments. None of them, however, seems quite slender or round enough. I'll get all that out of my man when I lock him up. I'll get it to-night if he dares come." "Why," Graham said, "do you announce your plans so accurately to us?" The detective's level smile widened. "You shouldn't ask that, Mr. Graham. I've caused the servants to know my plans. Mr. Paredes knows them. I wish every one in the house to know them. That is in order that the murderer, who is in the house, may come if he wishes." Katherine arose abruptly. "When you come down to it," she said, "you are accusing one of us. It's brutal, unfair--absurd." "I am a detective, Miss," Howells answered. "I have my own methods." Bobby stared at the slight protuberance in the breast pocket of the detective's coat. The cast of his footprint must be secreted there, and almost certainly the handkerchief which had been found beneath the bed. He shrank from his own thoughts. If he had consciously committed this murder he could understand a desire to get that evidence. Katherine had gone closer to the detective. "In any case," she urged him, "I wish you wouldn't try to spend the night in that room. It isn't pleasant. After what the doctor has said, it--well, it isn't safe." Howells burst out laughing. "Never fear, Miss. I'm content to give Doctor Groom's spirits as much chance to take a fall out of me as anybody. I'll be going up now." He bowed. "Good-night to you all, and pleasant dreams." He opened the door and slipped into the darkness of the private staircase. They heard him, after he had closed the door, climbing upward. Katherine shivered.