"Has anyone left the house since the discovery; that is, as far as you know?" he queried at length.

"No one," said Sir Lyster.

"The servants, of course, have access to this room?"

"Yes; but only Walters, my butler, is likely to come here in the evening, except, of course, my secretary."

"Where does he dine?"

"Miss Blair," corrected Sir Lyster, "always takes her meals in her own sitting-room, where she works. It is situated at the back of the house on the ground floor."

Again Malcolm Sage was silent, this time for a longer period.

"So far as you know, then," he said at length, addressing Sir Lyster, "only three people in the house were acquainted with the existence of the doc.u.ment; you, the Prime Minister, and Lord Beamdale."

Sir Lyster inclined his head.

"You are certain of that?" Malcolm Sage looked up swiftly and keenly.

"Your secretary and Lady Grayne, for instance, they knew nothing about it?"

"Nothing; of that I am absolutely certain," replied Sir Lyster coldly.

"And the nature of the doc.u.ment?" enquired Malcolm Sa'ge.

Sir Lyster looked across at Mr. Llewellyn John, who turned interrogatingly to Lord Beamdale.

"I am afraid it is of too private a nature to----" he hesitated.

"If you require me to trace something," said Malcolm Sage evenly, "you must at least tell me what that something is."

"It is a doc.u.ment which----" began Lord Beamdale, then he, too, paused.

"But, surely, Sage," broke in Mr. Llewellyn John, "is it not necessary to know the actual contents?"

"If you had lost something and would not tell me whether it was a dog or a diamond, would you expect me to find it?"

"But----" began Mr. Llewellyn John.

"I'm afraid we are wasting time, gentlemen," said Malcolm Sage, rising. "I would suggest Scotland Yard. The official police must work under any handicap imposed. I regret that I am unable to do so."

He walked across to the chair where lay his cap and coat.

"Now, Sage," said Mr. Llewellyn John tactfully, "you mustn't let us down, you really mustn't." Then turning to Sir Lyster, he said, "I can see his point. If he doesn't know the nature of the doc.u.ment, he cannot form a theory as to who is likely to have taken it. Perhaps under the circ.u.mstances, Grayne, we might take Sage into our confidence; at least to such extent as he thinks necessary."

Sir Lyster made no response, whilst Lord Beamdale, whose economy in words had earned for him the sobriquet of "Lord Dumbeam," sat with impa.s.sive face.

"Perhaps I can help you," said Malcolm Sage, still standing by the chair on which lay his cap and coat. "At the end of every great war the Plans Departments of the Admiralty and the War Office are busy preparing for the next war. I suggest that this doc.u.ment was the Admiralty draft of a plan of operations to be put into force in the event of war occurring between this country and an extremely friendly power. It was submitted to the War Office for criticism and comment as far as land-operations were concerned. Another power, unfriendly to the friendly power, would find in this doc.u.ment a very valuable red-herring to draw across the path of its own perplexities."

"Good heavens!" cried Mr. Llewellyn John, starting upright in his chair. "How on earth did you know?"

"It seems fairly obvious," said Malcolm Sage, as he returned to his chair and resumed his stroking of the sphinx's back. "Who else knew of the existence of the doc.u.ment?" he enquired.

"No one outside the Admiralty and the War----" Sir Lyster stopped suddenly.

From the corridor, apparently just outside the library door, came the sound of a suppressed scream, followed by a b.u.mp against the woodwork.

Rising and moving swiftly across the room, Sir Lyster threw open the door, revealing a gap of darkness into which a moment later slid two figures, a pretty, fair-haired girl and a wizened little j.a.panese with large round spectacles and an automatic smile.

"I'm so sorry, Sir Lysier," faltered the girl, as she stepped timidly into the room, "but I was frightened. Someone had switched off the lights and I ran into----" She turned to the j.a.panese, who stood deprecating and nervous on the threshold.

"I lose my pa.s.sage," he said, baring his teeth still further; "I go to find cigarette-case of my master. He leave it in beelyard-room. I go----"

With a motion of his hand, Sir Lyster dismissed the man, who slipped away as if relieved at getting off so lightly.

"You are up late, Miss Blair," he said coolly, turning to the girl.

"I'm so sorry," she said; "but Lady Grayne gave me some letters, and there was so much copying for you that----" She paused, then added nervously, "I didn't know it was so late."

"You had better go to bed, now," said Sir Lyster.

With a charming smile she pa.s.sed out, Sir Lyster closing the door behind her. As he turned into the room his eye caught sight of the chair in which Malcolm Sage had been sitting.

"Where is Mr. Sage?" He looked from Mr. Llewellyn John to Lord Beamdale.

As he spoke Malcolm Sage appeared from the embrasure of the window through which he had entered, and where he had taken cover as Sir Lyster rose to open the door.

"You see, Sage is not supposed to be here," explained Mr. Llewellyn John.

"Your secretary has an expensive taste in perfume," remarked Malcolm Sage casually, as he resumed his seat. "It often characterises an intensely emotional nature," he added musingly.

"Emotional nature!" repeated Sir Lyster. "As a matter of fact she is extremely practical and self-possessed. You were saying----" he concluded with the air of a man who dismisses a trifling subject in favour of one of some importance.

"Diplomatists should be trained physiognomists," murmured Malcolm Sage. "A man's mouth rarely lies, a woman's never."

Sir Lyster stared.

"Now," continued Malcolm Sage, "I should like to know who is staying here."

Sir Lyster proceeded to give some details of the guests and servants.

The domestic staff comprised twenty-one, and none had been in Sir Lyster's employ for less than three years. They were all excellent servants, of irreproachable character, who had come to him with good references. Seventeen of the twenty-one lived in the house. There were also four lady's-maids and five men-servants attached to the guests. Among the men-servants was Sir Jeffrey Trawler's j.a.panese valet.

There was something in Sir Lyster's voice as he mentioned this fact that caused Malcolm Sage to look up at him sharply.

"The man you have just seen," Sir Lyster explained. "He has been the cause of some little difficulty in the servants'-hall. They object to sitting down to meals with a Chinaman, as they call him.

"He seems intelligent?" remarked Malcolm Sage casually.

"On the contrary, he is an extremely stupid creature," was the reply.

"He is continually losing himself. Only yesterday morning I myself found him wandering about the corridor leading to my own bedroom.