“You failed to keep your engagement last night. I’ll give you just one more chance. Meet me to-night at the same place, 8:30 sharp, and be ready to come to some definite understanding with me. If you fail me this time I will consider myself absolved from my oath.” “Nick, this is the key to the whole tragedy.” “I think so, too.” “The note was never delivered.” “Certainly not.” “Why?” “For want of an opportunity--that’s clear.” “She may have backed down after writing it.” “You believe the note was intended for Gay, and that he gave her the slip to-day before she had a chance to get it to him?” “Right you are, lad.” “Did he go away from the office suddenly, without telling any one?” “Yes, except the office boy, whom he told just as he went out, leaving word for Redway that he would not be back during the day. Of course, Miss Langdon got the message indirectly.” “Well, what else?” “This.” Nick produced Redway’s watch and opened the back of the case. When he turned the inside toward Chick the latter looked upon the portrait of a lovely little girl of six or seven years of age. “Who is she?” asked Nick, as he gazed admiringly at the beautiful face. “That we must find out.” “Does she look like Redway?” “No. She has none of his features that I can see. Yet I believe it will be found that the child plays a prominent part in the tragedy by some indirect method.” “Why do you think so?” “Because there is a slight resemblance between her face and the face of the girl who was killed.” “Ah! that makes the child an important character in the case. What is your next move, Nick?” “There is no next move. It must be a series of moves in which I need your help and the aid of Ida.” “Well, map out your business.” “First, I want to find the mysterious woman. “Secondly, I want to find that little girl. “Thirdly, I want to discover where Estelle Langdon went last night--in order to discover her place of meeting with the party to whom she addressed that note. “Fourthly, I want Gay shadowed.” “Well, which part of the job is mine?” “I’m going to turn Gay over to you.” “All right. Gay’s my meat.” “I’ll look up the handsome, mysterious woman myself.” “And Ida?” “I’ll send Ida to the home of the dead girl to get information there.” “Perhaps you can give me an idea where I’ll find Gay?” “I think I can. Go down to the Borden Building, and wait till he comes there.” “To-night?” “Certainly! He’ll wait till some of the excitement dies out in that vicinity. Then he’ll visit that private office, or I am greatly mistaken.” Ida was brought into the case at this stage and instructed in the part she was expected to play. CHAPTER VIII. NICK BEGINS TO SOLVE THE RIDDLE. Having partaken of a hasty supper, and having changed his disguise, Nick went downtown again to the neighborhood of the tragedy.