In the famous white drawing-room at Beaumanoir House Sybil Hanbury was preparing to end a solitary evening by the simple process of going to bed. The butler, a martyr to punctilio, had insisted on lighting every jet in the chandeliers and in the sconces on the walls, with the result that the vast apartment scintillated like a ball-room, accentuating the loneliness of the black-clad little figure of its sole occupant.

Sybil laid aside her book, and surveyed the splendid emptiness of the room with a smile of amusement for her monopoly of so much gorgeously upholstered space. But as she realized that her monopoly of the white drawing-room was only a detail in the much larger incongruity of her monopoly of the Piccadilly mansion, her face took a graver look.

"I trust that the Vincents will be ready to take me in next week," she mused with a touch of impatience. "The idea of a score of servants and an acre of ducal palace being run for a simple body like me is too ridiculous, especially with the rightful owner ready to take possession."

She had been both puzzled and attracted by her cousin at General Sadgrove's that afternoon. As a child she had heard so much contemptuous obloquy poured on the absent ne'er-do-well that, in spite of his generosity to Alec Forsyth and his consideration for herself, she had been prepared to cling to the old prejudice. It had, however, at once broken down under the pathetic plea for friendship which she had discerned in the Duke's troubled eyes, for her womanly insight told her that the new head of the family was under the influence of a mental strain almost amounting to physical distress.

"He looks like a man sitting on an infernal machine, listening to the tick-tack of the clock-work," she reflected. "Yet I don't think he's wicked, or the sort of person with a past likely to fly up and hit him in the face. I wish I knew what he is grizzling about, so that Alec and I could do him a good turn in exchange for his benevolence."

She had risen with the intention of retiring to her own room, when the butler entered hurriedly, and with traces of well-disciplined agitation on his episcopal countenance. Mr. Prince had grown gray in the ducal service; but, beyond a slight fatherliness of manner, he did not presume on the fact towards the orphan scion of the great house.

"I really don't know, Miss, if I ought to disturb you so late on such a matter," he said. "Two men have called to see his Grace, and, failing him, insisted on my ascertaining if you would receive them."

"I know nothing of the Duke's affairs, and I am just going up to bed," Sybil replied, wondering at the usually correct retainer's excitement. "Besides, Prince, 'insist' is rather a curious word to use here," she added with a trace of asperity.

"I should not have ventured to repeat such an objectionable phrase, Miss, if it had not been used with a sort of authority," the butler hastened to put himself right. "I ought to have mentioned that they are Scotland Yard detectives, which accounts for my being a bit flurried."

Sybil promptly sat down again and bade Prince show the visitors in. She had no desire to pry into her cousin's business, nor did her reception of the police-officers imply any such intention. But at that moment her preconceived notion that the Duke was the center of a mystery took definite shape, and she was above all things loyal to the house. She decided that in her cousin's interest it would be wiser to see these men, and, if possible, fore-arm herself with a knowledge of their designs.

But when Prince returned it was to usher in not two men, but only one—a cadaverous, middle-aged person in the garb of a clergyman, who waited obsequiously near the door while his card was presented by the butler.

"I found when I got back into the hall that he'd sent the other man away, Miss—said there was no need for two of them to intrude upon you," explained Prince in an undertone.

Sybil nodded, but the furtive glances of the clerically dressed visitor caused her to call Prince back as he was retiring.

"I trust you didn't leave them alone in the hall?" she whispered.

"Oh, dear, no, Miss; William, the second footman, was on duty in the hall while I came to you," was the reply, uttered in a slightly injured tone.

Prince having taken a dignified departure, Sybil beckoned forward the individual whom his card proclaimed to be "Inspector Chantrey, Criminal Investigation Department." He advanced with a shambling walk and with deprecating gestures in keeping with his disguise; but Sybil formed the opinion that all his nervousness was not simulated. It struck her that he was listening intently as he threaded his way through the priceless Louis Seize garniture of the white drawing-room.

He stood before her at last, for all the world like a half-famished wolf in the presence of a very wide-awake and dainty lamb that had not the least intention of being devoured. He spoke hurriedly—almost perfunctorily, as though he set no great store by his questions or the answers to them; and all the time that listening attitude was noticeable.

"I called in the hope of finding his Grace at home," he began, with a half-note of interrogation.

"Well, the butler will have told you that he is not at home," said Sybil sharply.

"True; but servants are not always reliable, and I thought I had better see one of the family. Might I ask if the Duke is expected here to-night?"

"No, he isn't. What do you want him for?" snapped Sybil.

The aplomb of the question seemed to take the inquisitor back. He glanced curiously at the girl in the high-backed arm-chair, first scanning her tenacious little face, but quickly dropping his shifty eyes to the carelessly crossed shoes.

He began to "hem" and "ha."

"The fact of the matter is, we have had a communication from the county police at Prior's Tarrant, in respect of an assault on one of the servants in the park yesterday. The local people think the attack may have been intended for the Duke, and they have wired us to make inquiries."

The reason alleged for his visit sounded plausible, and in some degree might account for the hunted look she had surprised in the Duke's eyes. Yet she was not altogether satisfied. It was conceivable that the police should want to question the Duke, but the excuse for intruding on her at such an hour hardly seemed adequate.

"I am still at a loss to see how I can be of service to you in a matter of which I know nothing," she said, not attempting to keep the suspicion out of her voice.

"I only desired to make sure, madam, that the Duke was not at home. Having obtained that assurance from the fountain-head, pray permit me to withdraw," was the nervously spoken reply, punctuated by an awkward bow and the commencement of a hurried retreat. But the visitor had only taken three steps down the long vista of the room when the door was flung open, and Prince announced, with the air of one who springs a surprise:

"His Grace the Duke!"

Beaumanoir was very pale, but he advanced without hesitation, meeting Sibyl's interrogator half-way up the room. Startled as she was by her cousin's unexpected appearance, the girl intuitively rose and went forward, vaguely conscious of a desire to hear if the man repeated the same tale.

"Well, sir?" said the Duke, curtly.

Sybil hardly knew whether or no she was relieved when, word for word, the man repeated the reason he had just given her for his call. Watching her cousin's face, she saw the pallor yield to a flush of evident annoyance.

"Oh, yes; something of the kind occurred in the park at Prior's Tarrant," he angrily replied. "But all this about the man being mistaken for me is officious nonsense—too trivial to warrant your pushing your way into this young lady's presence at eleven o'clock at night. I shall complain to your superiors of this most impertinent intrusion."

"What could it mean?" Sybil asked herself. The man's nervous air—his attitude of listening—had disappeared. His sly face grew sleekly impudent under Beaumanoir's rebuke and it was quite jauntily that he answered:

"Then I'll bid your Grace good-night. Very possibly you'll reconsider the advisability of raising the question at Scotland Yard."

The clerical coat-tails went flapping down the room, the Duke following them to the door, where he handed their owner over to Prince, who was hovering in the hall. Having given a sharp order to "show the gentleman out," Beaumanoir returned to Sybil, humbly apologetic, but with signs of haste in his manner.

"My dear cousin, I am more than annoyed at Prince's laxity in admitting that fellow," he said, taking her hand. "It is fortunate that I chanced to look in in the hope of finding you up, and so was able to rid you of him. I came to leave a message for Alec in case he calls presently."

"But Alec is the pink of propriety," exclaimed Sibyl, laughing in spite of herself. "He doesn't call on an unprotected damsel, even if he is engaged to her, at eleven o'clock at night."

"Nevertheless, I believe that he will call here very shortly; and I should like him to be told that I am all right, and, in fact, that I am going out of town for a few days to the sea-side. I will communicate with him when I want him to enter on his secretarial duties. That is all, I think. I must really be off now."

But Sybil would not at once take his proffered hand. She remembered that he had mentioned that he was to spend the night at Alec's chambers, and this sudden derangement of plans, coupled with the lurking suggestion in his message, was, to say the least of it, mysterious. Looking into the tired eyes, she found again that expression of sleepless worry that had puzzled her. Why should it be necessary for this young man, newly come to great wealth and station, to notify his friend so feverishly that he was "all right," and in the same breath announce his retreat from London to some vague destination—not to his own country-seat?

"As you expect Alec here, wouldn't it be better to wait for him?" she urged; adding naÏvely, "I could even offer you a bed, if you would condescend to make yourself at home in your own house."

But Beaumanoir was in no mood to perceive the humor of the situation. He was clearly fidgeting to be gone, and Sybil could only conclude that he wanted to be gone before Alec arrived. With a girl's faith in her lover's power to surmount most difficulties, she decided to try and detain her cousin as long as possible; but her diplomacy was not called into play. Prince, now wearing an air of mild protest at all these excursions and alarums, appeared in the doorway to announce:

"Mr. Forsyth."

Beaumanoir was evidently disconcerted at not having made his exit in time; and Sybil, recognizing that there was something between the two men not for her ears, tactfully withdrew to the other end of the room, after smiling a greeting to her lover. She thought none the worse of him because he was too preoccupied to return it. She was beginning to discern an undercurrent of serious import beneath the happenings of the past half-hour.

"What made you break cover, old chap? You've given me a pretty scare," said Forsyth to the Duke. "When I found you'd gone, I came on here on the off-chance."

"I didn't think it fair to subject you to the sort of night you might have had with me as an inmate, so I cleared out," Beaumanoir replied, wearily. "I guessed you'd inquire here, so I called in to leave word that I was all right—up to date."

"You were not molested before quitting my chambers?"

"No. Why do you ask?"

"Because the place has been visited; it must have been after you left," said Forsyth, gravely. And he went on to relate how he had found the door broken open, and how he had met two suspicious-looking men on the stairs, one dressed as a clergyman and the other in shabby tweeds.

"Dressed as a clergyman?" cried Beaumanoir, startled into forgetfulness of Sybil's presence in the room. "Then, Alec, I have stood face to face with death in this house not ten minutes ago. I found your sham parson here, professing to be an official detective; but I doubted him from the first."

His raised tones reached Sybil, who realized that the house of Beaumanoir was confronted by no ordinary emergency. What the peril could be that threatened her noble relative she had no means of knowing, or any wish to know; but the Duke's description of himself as standing "face to face with death" amid the seeming security of his own white drawing-room touched her with the icy hand of unknown dread, and, moreever, filled her with a sense of responsibility. The man who was not safe under the dazzling lights of that splendid apartment, with a host of servants within call, was going forth into all the insecurity of the London streets at midnight because, her instinct told her, he would not expose her to the same danger.

Her cousin's chivalry appealed not only to her loyalty to the house, but to that protective impulse which springs readily in every woman's heart.

"I couldn't help overhearing you," she said, coming forward. "I, too, doubted that man—very strongly. I am sure he meant no good. But what I want to say, Cousin Charles, is that you must remain here to-night. If you go out of the house, I shall go also."

Forsyth shot a grateful look at her.

"The best possible plan," he said, quickly. "Now, don't be obstinate, Duke. The man has left the premises, I presume? Good! That being so, we shall be a poor lot if we can't prevent his getting in again, which he is hardly likely to attempt. There is nothing to hinder you from spending a quiet night here, without the slightest risk of unpleasantness either to Sybil or to yourself, and in the morning you and I can talk over your future movements at leisure."

"And I quite meant what I said," Sybil added, firmly. "If you won't stay here, you will put me to the inconvenience of turning out and going to an hotel at twelve o'clock at night. I have no intention of being forced into the horrid feeling that I am keeping you from the shelter of your own roof."

Under the pleading of the two pairs of kindly eyes turned on him Beaumanoir wavered. The chance of sleep and rest was tempting. He stepped to the door, and found Prince in the great entrance-hall.

"That man who called himself a detective has gone?" he inquired. "You are sure there is no mistake about it? You showed him to the door yourself, and saw him out?"

"And secured the door immediately afterwards, your Grace. Mr. Forsyth will bear me out in that; I had to withdraw the bolts to admit him."

Beaumanoir returned to the drawing-room.

"You are both very good, and I will stay for to-night only," he assented. "I wish I could make the explanation I owe you, but—well, I am the victim of circumstances."

"The explanation will keep," said Forsyth, bluntly. "May I stay too?"

The permission was, of course, accorded, and Sybil bade them good-night and retired to her room, giving orders on the way for two adjoining bedrooms to be prepared for them. The two men went into the smoking-room for a whisky and cigarette while the rooms were being got ready; but each with tacit consent avoided the topic of the moment. The one idea in Alec's mind was to let Beaumanoir have a good sleep, and persuade him into a serious discussion in the morning.

They parted at the door of their bedrooms on the first floor, where the late Duke's valet, who was still in the house, had done everything possible to cope with the sudden emergency. Pajamas had been routed out, and toilet requisites provided. The windows of both rooms looked out over the ceaseless traffic of Piccadilly, so that no danger could be apprehended from that quarter; yet Forsyth sat for a long time before turning in to bed. In his ignorance of what was the source of the Duke's danger, he had been loath to excite remark among the servants by fussing about the proper locking up of the mansion; but the stately tread of Prince going his rounds reassured him on that point, and eventually he slept.

In the meanwhile, Sybil, in her room at the other end of the same corridor, was finding a still greater difficulty in composing herself to rest. The events of the evening, in such startling contrast with the normal calm of the dignified establishment that had been her home, had unsettled—not to say alarmed—her, and she felt no inclination to the lace-edged pillow that usually wooed her to willing slumbers. She was a sound, healthy girl, untroubled by nerves; but she felt a singular need for alertness, unreasonable perhaps, but imperative.

The Duke's anxiety to make sure that the clerically dressed individual had really left the house had impressed her; and now, too late for inquiry, she remembered that she had omitted to mention that two men had called, one of them not having been shown into her presence. The latter, Prince had said, had been dismissed by his colleague; but his departure had only been witnessed by William, the second footman—a dreamy servant at the best of times, and unreliable by reason of a hopeless attachment to the senior housemaid. The thought thrilled Sybil that the other man, having hoodwinked the footman, might still be in the house, concealed in one of the many unused rooms.

The idea of a lurking prowler, biding his time in the stillness of the sleeping household, kept her wakeful. Once or twice she looked out into the corridor; but the flicker of her candle only showed two rows of closed doors, without a sign of life, and each time she went back and tried to fix her attention on a book. So the night dragged into the small hours; and about three o'clock, after a longer interval than before, she determined to take one more peep and then get into bed.

She had already grasped the door-handle, when she withdrew her hand as though it had been stung by an adder. A faint scrooping sound told her that someone was doing something in the corridor, and half a minute's strained listening told her that, whatever that something was, it was persistent and continuous. It went on and on, like the drone of a bee in a bottle.

Silently crossing the room, she turned down her gas to a pin-point and blew out the candle with which she had intended to investigate. Then she returned to the door, and, opening it noiselessly, tiptoed into the outer darkness. Here the sound, though still faint, was more distinctly audible, and she was able to locate it at the door of the room occupied by the Duke. The discovery left her no time for fear, or even for conjecture. There was only one thing to be done—to rouse Alec and the Duke, but without, till that supreme moment, alarming the unseen manipulator at her cousin's door. Thus would she narrow the time at the disposal of that mysterious person for revising his plans and effecting his escape.

The thick pile carpet made for silence, and she stole quietly along the broad passage, touching and counting the doors till she reached that of Forsyth's room—only a few feet from the gentle buz-buz that had attracted her attention, and only a few feet from someone stealthily at work in the dark. A steady snore from the interior of the Duke's chamber explained his complacence under that uncanny tampering with his approaches.

Again giving herself no time for fear, Sybil beat a rat-tat on Forsyth's door, calling him by name. The sound at the next door immediately ceased, an instant of intense silence following, and then almost simultaneously two things happened. An iron grip settled on the girl's wrist, just as Forsyth flung open the door of his room, in which he had wisely turned the gas full on as he leaped out of bed. The light streamed into the corridor and shone upon a man in shabby tweeds and bowler hat, who was holding Sybil, but not so hampered that he was prevented from drawing a revolver and aiming straight at Forsyth's head.

Whether he intended to fire or offer an ultimatum was not demonstrated, for before he could do either he was taken in the rear and found himself a target. There stood the Duke in his pajamas, with a handy little Smith and Wesson not a foot from the intruder's temples, and with his left hand significantly extended.

"Give me that pistol," he said, sternly.

Beaumanoir was dealing with a tangible foe at last, and with a thrill of racial pride Sybil noted the light of battle in her relative's eye. It was, therefore, more than a shock to her when the Duke, having relieved the tweed-coated lurker of his weapon, calmly added:

"Now, sir, if you will be good enough to march in front of me down to the front door, I will let you out. You two," he continued, addressing Sybil and Forsyth in the same quiet tones, "will greatly oblige me by not raising any alarm or disturbing the servants while I am gone."

"I am coming downstairs with you," said Forsyth, drily.

When the procession of three, led by the stranger with a brace of pistols at his head, had filed off to the grand staircase, Sybil ran back to her room and fetched her candle. An inspection of the Duke's door showed that a panel had been partially cut out with a watch-spring saw, which was still sticking in the almost invisible fissure.