“As soon as he heard the door close, he drove off, making but one stop on his way here, and that at Fifty-eighth Street, where his carriage was blocked for a minute or two. “Arriving here, as the lady did not get out, he got down from his box and opened the door, to find her unconscious. He gave the alarm; the woman was carried into her home, and a doctor soon coming pronounced her dead.” “No one was known to have been in the carriage with her?” asked Nick. “No. That is the great mystery. I was disposed at first to look upon it as suicide. I have not abandoned that idea entirely yet, though all the physicians and surgeons who have examined the body say it is not probable. “However, the body lies in the parlor. Go and look at it, and after you have made your first investigation, I shall be obliged if you will come and talk with me about it.” The coroner stepped back and opened the door for Nick to pass through, closing the door after him and going his way. Nick passed into the parlor, and there found Mrs. Constant lying in the box the undertaker had provided. He stood looking down upon her face, thinking that death had brought its changes and sharpened peculiarities of features that he had not noticed in life. While he looked, the undertaker came from a rear room, looking at him inquiringly. Nick said, quietly: “I am Mr. Carter, the detective.” “Oh, yes; Mrs. Constant is expecting you. Indeed, she is very anxious to see you.” Nick looked up in great surprise, saying: “Mrs. Constant?” He pointed to the body lying within the box. The undertaker smiled in a melancholy way, and said: “That is what has puzzled and confused people so. But let me take you to Mrs. Constant. She has been asking every minute if you have come.” Nick followed the undertaker up the stairs to the door of a room in the front of the house, at which the undertaker rapped lightly. A maidservant opened the door, and when the undertaker said that Mr. Carter was there, flung it wide open, saying: “Come, Mr. Carter, Mrs. Constant will be glad to see you.” As Nick stepped into the room, the maidservant spoke to a lady sitting in the corner, telling her that Mr. Carter was there. The lady arose immediately, and advanced to meet Nick. At once Nick saw that she was Mrs. Constant in the life. Her face showed the distress she was suffering, for it was pale and haggard, and its lines deeply marked. The resemblance between the woman before him and the one lying still in death in the room below was astonishing. Mrs. Constant took Nick’s hand, attempting to speak, but broke into uncontrollable sobs. However, she controlled herself in a few minutes, and said: “This is the end, Mr. Carter. It is the last. It can go no further.” “I cannot understand it,” said Nick. “The paper said it was you who was killed.” “I wish it was myself who had been killed,” cried Mrs. Constant. “It was my twin sister, Ethel. But it was I he intended to kill.”