"The police," said the little man, "do not think of things that Hercule Poirot thinks of."

"I may have run in there for a minute just before dinner," mused Lily Margrave, "or it may have been the night before. I wore the same dress then. Yes, I am almost sure it was the night before."

"I think not," said Poirot evenly.

"Why?"

He only shook his head slowly from side to side.

"What do you mean?" whispered the girl.

She was leaning forward, staring at him, all the color ebbing out of her face.

"You do not notice, Mademoiselle, that this fragment is stained? There is no doubt about it, that stain is human blood."

"You mean -?"

"I mean, Mademoiselle, that you were in the Tower room after the crime was committed, not before. I think you will do well to tell me the whole truth, lest worse should befall you."

He stood up now, a stern little figure of a man, his forefinger pointed accusingly at the girl.

"How did you find out?" gasped Lily.

"No matter, Mademoiselle. I tell you Hercule Poirot knows. I know all about Captain Humphrey Naylor, and that you went down to meet him that night."

Lily suddenly put her head down on her arms and burst into tears. Immediately Poirot relinquished his accusing att.i.tude.

"There, there, my little one," he said, patting the girl on the shoulder. "Do not distress yourself. Impossible to deceive Hercule Poirot; once realize that and all your troubles will be at an end. And now you will tell me the whole story, will you not? You will tell old Papa Poirot?"

"It is not what you think, it isn't, indeed. Humphrey - my brother - never touched a hair of his head."

"Your brother, eh?" said Poirot. "So that is how the land lies. Well, if you wish to save him from suspicion, you must tell me the whole story now, without reservations."

Lily sat up again, pushing back the hair from her forehead. After a minute or two, she began to speak in a low, clear voice.

"I will tell you the truth, M. Poirot. I can see now that it would be absurd to do anything else. My real name is Lily Naylor, and Humphrey is my only brother. Some years ago, when he was out in Africa, he discovered a gold mine, or rather, I should say, discovered the presence of gold. I can't tell you this part of it properly, because I don't understand the technical details, but what it amounted to was this: "The thing seemed likely to be a very big undertaking, and Humphrey came home with letters to Sir Reuben Astwell in the hopes of getting him interested in the matter. I don't understand the rights of it even now, but I gather that Sir Reuben sent out an expert to report, and that he subsequently told my brother that the expert's report was unfavorable and that he, Humphrey, had made a great mistake. My brother went back to Africa on an expedition into the interior and was lost sight of. It was a.s.sumed that he and the expedition had perished.

"It was soon after that that a company was formed to exploit the Mpala Cold Fields. When my brother got back to England he at once jumped to the conclusion that these gold fields were identical with those he had discovered. Sir Reuben Astwell had apparently nothing to do with this company, and they had seemingly discovered the place on their own. But my brother was not satisfied; he was convinced that Sir Reuben had deliberately swindled him.

"He became more and more violent and unhappy about the matter. We two are alone in the world, M. Poirot, and as it was necessary then for me to go out and earn my own living, I conceived the idea of taking a post in this household and trying to find out if any connection existed between Sir Reuben and the Mpala Gold Fields. For obvious reasons I concealed my real name, and I'll admit frankly that I used a forged reference.

"There were many applicants for the post, most of them with better qualifications than mine, so - well, M. Poirot, I wrote a beautiful letter from the d.u.c.h.ess of Perthshire who I knew had just gone to America. I thought a d.u.c.h.ess would have a great effect upon Lady Astwell, and I was quite right. She engaged me on the spot.

"Since then I have been that hateful thing, a spy, and until lately with no success. Sir Reuben is not a man to give away his business secrets, but when Victor Astwell came back from Africa he was less guarded in his talk, and I began to believe that, after all, Humphrey had not been mistaken. My brother came down here about a fortnight before the murder, and I crept out of the house to meet him secretly at night. I told him the things Victor Astwell had said, and he became very excited and a.s.sured me I was definitely on the right track.

"But after that things began to go wrong; someone must have seen me stealing out of the house and have reported the matter to Sir Reuben. He became suspicious and hunted up my references, and soon discovered the fact that they were forged. The crisis came on the day of the murder. I think he thought I was after his wife's jewels. Whatever his suspicions were, he had no intention to allow me to remain any longer at Mon Repos, though he agreed not to prosecute me on account of the references. Lady Astwell took my part throughout and stood up valiantly to Sir Reuben."

She paused. Poirot's face was very grave.

"And now, Mademoiselle," he said, "we come to the night of the murder."

Lily swallowed hard and nodded her head.

"To begin with, M, Poirot, I must tell you that my brother had come down again, and that I had arranged to creep out and meet him once more. I went up to my room, as I have said, but I did not go to bed. Instead, I waited till I thought everyone was asleep, and then stole downstairs again and out by the side door. I met Humphrey and acquainted him in a few hurried words what had occurred. I told him that I believed the papers he wanted were in Sir Reuben's safe in the Tower room, and we agreed as a last desperate adventure to try and get hold of them that night.

"I was to go in first and see that the way was clear. I heard the church clock strike twelve as I went in by the side door. I was halfway up the stairs leading to the Tower room, when I heard a thud of something falling, and a voice cried out, 'My G.o.d!' A minute or two afterward the door of the Tower room opened, and Charles Leverson came out. I could see his face quite clearly in the moonlight, but I was crouching some way below him on the stairs where it was dark, and he did not see me at all.

"He stood there a moment swaying on his feet and looking ghastly. He seemed to be listening; then with an effort he seemed to pull himself together and, opening the door into the Tower room, called out something about there being no harm done. His voice was quite jaunty and debonair, but his face gave the lie to it. He waited a minute more, and then slowly went on upstairs and out of sight.

"When he had gone I waited a minute or two and then crept to the Tower room door, I had a feeling that something tragic had happened. The main light was out, but the desk lamp was on, and by its light I saw Sir Reuben lying on the floor by the desk. I don't know how I managed it, but I nerved myself at last to go over and kneel down by him. I saw at once that he was dead, struck down from behind, and also that he couldn't have been dead long; I touched his hand and it was still quite warm. It was just horrible, M. Poirot. Horrible!"

She shuddered again at the remembrance.

"And then?" said Poirot, looking at her keenly.

Lily Margrave nodded.

"Yes, M. Poirot, I know what you are thinking. Why didn't I give the alarm and raise the house? I should have done so, I know, but it came over me in a flash, as I knelt there, that my quarrel with Sir Reuben, my stealing out to meet Humphrey, the fact that I was being sent away on the morrow, made a fatal sequence. They would say that I had let Humphrey in, and that Humphrey had killed Sir Reuben out of revenge. If I said that I had seen Charles Leverson leaving the room, no one would believe me.

"It was terrible, M. Poirot! I knelt there, and thought and thought, and the more I thought the more my nerve failed me. Presently I noticed Sir Reuben's keys which had dropped from his pocket as he fell. Among them was the key of the safe, the combination word I already knew, since Lady Astwell had mentioned it once in my hearing. I went over to that safe, M. Poirot, unlocked it and rummaged through the papers I found there.

"In the end I found what I was looking for. Humphrey had been perfectly right. Sir Reuben was behind the Mpala Gold Fields, and he had deliberately swindled Humphrey. That made it all the worse. It gave a perfectly definite motive for Humphrey having comitted the crime. I put the papers back in the safe, left the key in the door of it, and went straight upstairs to my room. In the morning I pretended to be surprised and horror-stricken, like everyone else, when the housemaid discovered the body."

She stopped and looked piteously across at Poirot.

"You do believe me, M. Poirot. Oh, do say you believe me!"

"I believe you, Mademoiselle," said Poirot; "you have explained many things that puzzled me. Your absolute certainty, for one thing, that Charles Leverson had committed the crime and at the same time your persistent efforts to keep me from coming down here."

Lily nodded.

"I was afraid of you," she admitted frankly. "Lady Astwell could not know, as I did, that Charles was guilty, and I couldn't say anything. I hoped against hope that you would refuse to take the case."

"But for that obvious anxiety on your part, I might have done so," said Poirot dryly.

Lily looked at him swiftly, her lips trembled a little.

"And now, M. Poirot, what - what are you going to do?"

"As far as you are concerned, Mademoiselle, nothing. I believe your story, and I accept it. The next step is to go to London and see Inspector Miller."

"And then?" asked Lily.

"And then," said Poirot, "we shall see."

Outside the door of the study he looked once more at the little square of stained green chiffon which he held in his hand.

"Amazing," he murmured to himself complacently, "the ingenuity of Hercule Poirot."

Detective Inspector Miller was not particularly fond of M. Hercule Poirot. He did not belong to that small band of inspectors at the Yard who welcomed the little Belgian's cooperation. He was wont to say that Hercule Poirot was much overrated. In this case he felt pretty sure of himself, and greeted Poirot with high good humor in consequence.

"Acting for Lady Astwell, are you? Well, you have taken up a mare's nest in that case."

"There is, then, no possible doubt about the matter?"

Miller winked. "Never was a clearer case, short of catching a murderer absolutely red-handed."

"M. Leverson has made a statement, I understand?"

"He had better have kept his mouth shut," said the detective. "He repeats over and over again that he went straight up to his room and never went near his uncle. That's a fool story on the face of it."

"It is certainly against the weight of evidence," murmured Poirot. "How does he strike you, this young M. Leverson?"

"Darned young fool."

"A weak character, eh?"

The inspector nodded.

"One would hardly think a young man of that type would have the - how do you say it - the bowels to commit such a crime."

"On the face of it, no," agreed the inspector. "But, bless you, I have come across the same thing many times. Get a weak, dissipated young man into a corner, fill him up with a drop too much to drink, and for a limited amount of time you can turn him into a fire-eater. A weak man in a corner is more dangerous than a strong man."

"That is true, yes; that is true what you say."

Miller unbent a little further.

"Of course, it is all right for you, M. Poirot," he said. "You get your fees just the same, and naturally you have to make a pretense of examining the evidence to satisfy her Ladyship. I can understand all that."

"You understand such interesting things," murmured Poirot, and took his leave.

His next call was upon the solicitor representing Charles Leverson. Mr Mayhew was a thin, dry, cautious gentleman. He received Poirot with reserve. Poirot, however, had his own ways of inducing confidence. In ten minutes' time the two were talking together amicably.

"You will understand," said Poirot, "I am acting in this case solely on behalf of M. Leverson. That is Lady Astwell's wish. She is convinced that he is not guilty."

"Yes, yes, quite so," said Mr Mayhew without enthusiasm. Poirot's eyes twinkled. "You do not perhaps attach much importance to the opinions, of Lady Astwell?" he suggested.

"She might be just as sure of his guilt tomorrow," said the lawyer dryly.

"Her intuitions are not evidence certainly," agreed Poirot, "and on the face of it the case looks very black against this poor young man."

"It is a pity he said what he did to the police," said the lawyer; "it will be no good his sticking to that story."

"Has he stuck to it with you?" inquired Poirot.

Mayhew nodded. "It never varies an iota. He repeats it like a parrot."

"And that is what destroys your faith in him," mused the other. "Ah, don't deny it," he added quickly, holding up an arresting hand. "I see it only too plainly. In your heart you believe him guilty. But listen now to me, to me, Hercule Poirot. I present to you a case.

"This young man comes home, he has drunk the c.o.c.ktail, the c.o.c.ktail, and again the c.o.c.ktail, also without doubt the English whisky and soda many times. He is full of, what you call it? the courage Dutch, and in that mood he lets himself into the house with his latchkey, and he goes with unsteady steps up to the Tower room. He looks in at the door and sees in the dim light his uncle, apparently bending over the desk.

"M. Leverson is full, as we have said, of the courage Dutch. He lets himself go, he tells his uncle just what he thinks of him. He defies him, he insults him, and the more his uncle does not answer back, the more he is encouraged to go on, to repeat himself, to say the same thing over and over again, and each time more loudly. But at last the continued silence of his uncle awakens an apprehension. He goes nearer to him, he lays his hand on his uncle's shoulder, and his uncle's figure crumples under his touch and sinks in a heap to the ground.

"He is sobered, then, this M. Leverson. The chair falls with a crash, and he bends over Sir Reuben. He realizes what has happened, he looks at his hand covered with something warm and red. He is in a panic then, he would give anything on earth to recall the cry which has just sprung from his lips, echoing through the house. Mechanically he picks up the chair, then he hastens out through the door and listens. He fancies he hears a sound, and immediately, automatically, he pretends to be speaking to his uncle through the open door.

"The sound is not repeated. He is convinced he has been mistaken in thinking he heard one. Now all is silence, he creeps up to his room, and at once it occurs to him how much better it will be if he pretends never to have been near his uncle that night. So he tells his story. Parsons at that time, remember, has said nothing of what he heard. When he does do so, it is too late for M. Leverson to change. He is stupid, and he is obstinate, he sticks to his story. Tell me, Monsieur, is that not possible?"

"Yes," said the lawyer, "I suppose in the way you put it that it is possible."

Poirot rose to his feet.

"You have the privilege of seeing M. Leverson," he said. "Put to him the story I have told you, and ask him if it is not true."

Outside the lawyer's office, Poirot hailed a taxi.

"348 Harley Street," he murmured to the driver.

Poirot's departure for London had taken Lady Astwell by surprise, for the little man had not made any mention of what he proposed doing. On his return, after an absence of twenty-four hours, he was informed by Parsons that Lady Astwell would like to see him as soon as possible. Poirot found the lady in her own boudoir. She was lying down on the divan, her head propped up by cushions, and she looked startlingly ill and haggard; far more so than she had done on the day Poirot arrived.

"So you have come back, M. Poirot?"

"I have returned, milady."

"You went to London?"

Poirot nodded.

"You didn't tell me you were going," said Lady Astwell sharply.

"A thousand apologies, milady, I am in error, I should have done so. La prochaine fois -"

"You will do exactly the same," interrupted Lady Astwell with a shrewd touch of humor. "Do things first and tell people afterward, that is your motto right enough."

"Perhaps it has also been milady's motto?" His eyes twinkled.

"Now and then, perhaps," admitted the other. "What did you go up to London for, M. Poirot? You can tell me now, I suppose?"

"I had an interview with the good Inspector Miller, and also with the excellent Mr Mayhew."

Lady Astwell's eyes searched his face.

"And you think, now -?" she said slowly.

Poirot's eyes were fixed on her steadily.

"That there is a possibility of Charles Leverson's innocence," he said gravely.

"Ah!" Lady Astwell moved suddenly, sending two cushions rolling to the ground. "I was right, then, I was right!"