"Ah," said Poirot, "that is curious."

"Why curious?" asked the secretary.

"Because of this."

Poirot pointed to a round irregular stain on the polished surface of the writing table.

"That is a bloodstain, mon ami."

"It may have spattered there," suggested Trefusis, "or it may have been made later, when they moved the body."

"Very possibly, very possibly," said the little man. "There is only the one door to this room?"

"There is a staircase here."

Trefusis pulled aside a velvet curtain in the corner of the room nearest the door, where a small spiral staircase lead upwards.

"This place was originally built by an astronomer. The stairs led up to the tower where the telescope was fixed. Sir Reuben had the place fitted up as a bedroom, and sometimes slept there if he was working very late."

Poirot went nimbly up the stairs. The circular room upstairs was plainly furnished, with a camp-bed, a chair and dressing table. Poirot satisfied himself that there was no other exit, and then came down again to where Trefusis stood waiting for him.

"Did you hear Mr. Leverson come in?" he asked.

Trefusis shook his head.

"I was fast asleep by that time."

Poirot nodded. He looked slowly round the room.

"Eh bien!" he said at last. "I do not think there is anything further here, unless-perhaps you would be so kind as to draw the curtains."

Obediently Trefusis pulled the heavy black curtains across the window at the far end of the room. Poirot switched on the light-which was masked by a big alabaster bowl hanging from the ceiling.

"There was a desk light?" he asked.

For reply the secretary clicked on a powerful green-shaded hand lamp, which stood on the writing table. Poirot switched the other light off, then on, then off again.

"C'est bien! I have finished here."

"Dinner is at half past seven," murmured the secretary.

"I thank you, M. Trefusis, for your many amiabilities."

"Not at all."

Poirot went thoughtfully along the corridor to the room appointed for him. The inscrutable George was there laying out his master's things.

"My good George," he said presently, "I shall, I hope, meet at dinner a certain gentleman who begins to intrigue me greatly. A man who has come home from the tropics, George. With a tropical temper-so it is said. A man whom Parsons tries to tell me about, and whom Lily Margrave does not mention. The late Sir Reuben had a temper of his own, George. Supposing such a man to come into contact with a man whose temper was worse than his own-how do you say it? The fur would jump about, eh?"

" 'Would fly' is the correct expression, sir, and it is not always the case, sir, not by a long way."

"No?"

"No, sir. There was my Aunt Jemima, sir, a most shrewish tongue she had, bullied a poor sister of hers who lived with her, something shocking she did. Nearly worried the life out of her. But if anyone came along who stood up to her, well, it was a very different thing. It was meekness she couldn't bear."

"Ha!" said Poirot, "it is suggestive-that."

George coughed apologetically.

"Is there anything I can do in any way," he inquired delicately, "to-er-a.s.sist you, sir?"

"Certainly," said Poirot promptly. "You can find out for me what colour evening dress Miss Lily Margrave wore that night, and which housemaid attends her."

George received these commands with his usual stolidity.

"Very good, sir, I will have the information for you in the morning."

Poirot rose from his seat and stood gazing into the fire.

"You are very useful to me, George," he murmured. "Do you know, I shall not forget your Aunt Jemima?"

Poirot did not, after all, see Victor Astwell that night. A telephone message came from him that he was detained in London.

"He attends to the affairs of your late husband's business, eh?" asked Poirot of Lady Astwell.

"Victor is a partner," she explained. "He went out to Africa to look into some mining concessions for the firm. It was mining, wasn't it, Lily?"

"Yes, Lady Astwell."

"Gold mines, I think, or was it copper or tin? You ought to know, Lily, you were always asking Reuben questions about it all. Oh, do be careful, dear, you will have that vase over!"

"It is dreadfully hot in here with the fire," said the girl. "Shall I-shall I open the window a little?"

"If you like, dear," said Lady Astwell placidly.

Poirot watched while the girl went across to the window and opened it. She stood there a minute or two breathing in the cool night air. When she returned and sat down in her seat, Poirot said to her politely: "So Mademoiselle is interested in mines?"

"Oh, not really," said the girl indifferently. "I listened to Sir Reuben, but I don't know anything about the subject."

"You pretended very well, then," said Lady Astwell. "Poor Reuben actually thought you had some ulterior motive in asking all those questions."

The little detective's eyes had not moved from the fire, into which he was steadily staring, but nevertheless, he did not miss the quick flush of vexation on Lily Margrave's face. Tactfully he changed the conversation. When the hour for good nights came, Poirot said to his hostess: "May I have just two little words with you, Madame?"

Lily Margrave vanished discreetly. Lady Astwell looked inquiringly at the detective.

"You were the last person to see Sir Reuben alive that night?"

She nodded. Tears sprang into her eyes, and she hastily held a black-edged handkerchief to them.

"Ah, do not distress yourself, I beg of you do not distress yourself."

"It's all very well, M. Poirot, but I can't help it."

"I am a triple imbecile thus to vex you."

"No, no, go on. What were you going to say?"

"It was about eleven o'clock, I fancy, when you went into the Tower room, and Sir Reuben dismissed Mr. Trefusis. Is that right?"

"It must have been about then."

"How long were you with him?"

"It was just a quarter to twelve when I got up to my room; I remember glancing at the clock."

"Lady Astwell, will you tell me what your conversation with your husband was about?"

Lady Astwell sank down on the sofa and broke down completely. Her sobs were vigorous.

"We-qua-qua-quarrelled," she moaned.

"What about?" Poirot's voice was coaxing, almost tender.

"L-l-lots of things. It b-b-began with L-Lily. Reuben took a dislike to her-for no reason, and said he had caught her interfering with his papers. He wanted to send her away, and I said she was a dear girl, and I would not have it. And then he s-s-started shouting me down, and I wouldn't have that, so I just told him what I thought of him.

"Not that I really meant it, M. Poirot. He said he had taken me out of the gutter to marry me, and I said-ah, but what does it all matter now? I shall never forgive myself. You know how it is, M. Poirot, I always did say a good row clears the air, and how was I to know someone was going to murder him that very night? Poor old Reuben."

Poirot had listened sympathetically to all this outburst.

"I have caused you suffering," he said. "I apologize. Let us now be very businesslike-very practical, very exact. You still cling to your idea that Mr. Trefusis murdered your husband?"

Lady Astwell drew herself up.

"A woman's instinct, M. Poirot," she said solemnly, "never lies."

"Exactly, exactly," said Poirot. "But when did he do it?"

"When? After I left him, of course."

"You left Sir Reuben at a quarter to twelve. At five minutes to twelve Mr. Leverson came in. In that ten minutes you say the secretary came along from his bedroom and murdered him?"

"It is perfectly possible."

"So many things are possible," said Poirot. "It could be done in ten minutes. Oh, yes! But was it?"

"Of course he says he was in bed and fast asleep," said Lady Astwell, "but who is to know if he was or not?"

"n.o.body saw him about," Poirot reminded her.

"Everybody was in bed and fast asleep," said Lady Astwell triumphantly. "Of course n.o.body saw him."

"I wonder," said Poirot to himself.

A short pause.

"Eh bien, Lady Astwell, I wish you good night."

George deposited a tray of early-morning coffee by his master's bedside.

"Miss Margrave, sir, wore a dress of light green chiffon on the night in question."

"Thank you, George, you are most reliable."

"The third housemaid looks after Miss Margrave, sir. Her name is Gladys."

"Thank you, George. You are invaluable."

"Not at all, sir."

"It is a fine morning," said Poirot, looking out of the window, "and no one is likely to be astir very early. I think, my good George, that we shall have the Tower room to ourselves if we proceed there to make a little experiment."

"You need me, sir?"

"The experiment," said Poirot, "will not be painful."

The curtains were still drawn in the Tower room when they arrived there. George was about to pull them, when Poirot restrained him.

"We will leave the room as it is. Just turn on the desk lamp."

The valet obeyed.

"Now, my good George, sit down in that chair. Dispose yourself as though you were writing. Tres bien. Me, I seize a club, I steal up behind you, so, and I hit you on the back of the head."

"Yes, sir," said George.

"Ah!" said Poirot, "but when I hit you, do not continue to write. You comprehend I cannot be exact. I cannot hit you with the same force with which the a.s.sa.s.sin hit Sir Reuben. When it comes to that point, we must do the make-believe. I hit you on the head, and you collapse, so. The arms well relaxed, the body limp. Permit me to arrange you. But no, do not flex your muscles."

He heaved a sigh of exasperation.

"You press admirably the trousers, George," he said, "but the imagination you possess it not. Get up and let me take your place."

Poirot in his turn sat down at the writing table.

"I write," he declared, "I write busily. You steal up behind me, you hit me on the head with the club. Crash! The pen slips from my fingers, I drop forward, but not very far forward, for the chair is low, and the desk is high, and, moreover, my arms support me. Have the goodness, George, to go back to the door, stand there, and tell me what you see."

"Ahem!"

"Yes, George?" encouragingly.