The detective fell face upward, and upon the instant that he reached that position his hands went up and grasped Slack by the throat. As the grip tightened, Slack struck out blindly, but his hands soon grew nerveless, while his eyes began to start from their sockets. At the right moment Nick, with a supreme effort, raised himself and threw his enemy backward, and the next instant was sitting on the man's chest. "Give up?" he asked. "Yes," came in a labored, husky voice. "I'm a quitter, all right." CHAPTER VI. THE MYSTERY OF ROOM M. Not until the detective had tied Slack's hands, removed his weapons, a pistol and knife, and propped him against the wall, did he move away. After he had bathed his ankle with water found in the kitchen and satisfied himself that the sprain was not a bad one, Nick opened his batteries on his prisoner. "Slack," he said, more in sorrow than in anger, "this is a strange part for you to play. What has come over you? In San Francisco you were an honest man, a defender of law and order." "Every man for himself! that's my motto," replied Slack sullenly. "That is dodging the question. What have I ever done to you, that you should jump me?" "You have stuck your nose into my concerns, that's what you have done," was Slack's savage outburst. Nick looked at the man curiously. "I think I understand," he said quietly. "You are under the thumb of Cora Reesey, otherwise Madame Ree. She has taken you into her good graces again. You came here to meet her. You find her gone, and you get the notion into your head that I am responsible for her disappearance. Well, you are wrong. I have had no dealings of any kind with Madame Ree since her arrival in St. Louis. I had no hand in sending her away, and I don't know where she is. It is very evident, though, that she has given you the icy mitt." Slack's face was a study while Nick was speaking. "Do you mean to say that you have neither driven her, nor given a tip to the chief of police which has caused her to be driven from St. Louis?" "I am not a liar," returned Nick coldly. "What I say goes with those who know me." "I beg your pardon," said Slack humbly. "I have been a fool. I thought you had mixed up in my affairs--for I'm going to marry Madame Ree--and I made up my mind to get even." "When did you arrive in town?" "Yesterday. Cora was expecting me; had written me to come. I found her gone. I learned from a police officer of my acquaintance that you were here, and I at once connected Cora's disappearance with your presence." "You saw me quite by accident, didn't you?" "Yes. I have been laying for you all day. I hired these rooms, and my plan was to lure you here, jump you, and keep you a prisoner until I had found Cora, who might deal with you as she liked." "You were not holding out an alluring prospect for me, Slack," said Nick dryly.