“Now, Chick,” said Nick. “To send Edith to Mrs. Constant, and then you and I will take up the most difficult part of the work.” In a few moments these two shrewd detectives were on their way to the neighborhood of the Constant residence. As they were riding uptown in the car, Nick said: “Mrs. Constant’s theory is that Ethel was killed by a person who had intended to kill her, but was misled by the strong resemblance between Ethel and herself. “That resemblance is great,” admitted Nick. “I was misled by it myself twice—once shortly after I had been introduced to Mrs. Constant, and again when Ethel brought that package to me from Blanche Constant.” “But, chief,” said Chick, “you did not know at that time that Mrs. Constant had a twin sister; the mistake was a natural one. But if Masson was as well acquainted with Mrs. Constant as he seems to be it would be strange if he did not know of that twin sister.” “And would not have been easily misled,” said Nick. “You have struck a point that must be investigated.” “And there is a point on the other side,” said Chick. “The hard thing in adopting the theory of Mrs. Constant is that a man of the kind Masson is should commit murder, especially in cold blood. “Now, suppose that Masson did not know of the twin sister, suppose he climbed into that coach under the notion that Mrs. Constant was in it. Since it was Ethel Romney, she, of course, denied that she was Blanche or that she knew Masson, perhaps, to his anger, leading to the murder and the reason for it.” “That is,” said Nick, “supposing it to have been Masson, and that he lost his temper, he lost control of himself, in that denial.” “Yes, that is what I mean,” said Chick. “Well,” said Nick, “it all means that we have plenty of work to do and a lot of vexatious little inquiries. Whoever it was that got into that coach, whether it was Masson or some one else, in my opinion crept into the coach while it was standing in front of that dressmaker’s establishment to which Ethel Romney went.” This conversation had occupied the greater portion of their trip uptown. As they stepped off the car, Nick saw the man Rawson, who was the driver for Mrs. Constant. He appeared to be looking for some one. Rawson brightened up as Nick approached, and said: “I have been looking for you, Mr. Carter, because I have got something to say. I have been thinking over that ride last night, and especially since you asked me to-day about its being likely that any one got into that carriage.” “Yes, have you thought of anything more?” said Nick. “Well, yes,” said Rawson. “It isn’t much, but, then, I ought to tell you. You see, I didn’t think much when you asked me that question, but since I have. “The lady was in a great hurry to get back home, and as soon as she got into the carriage from that dressmaker’s I touched up the horses and started off at a good gait.