CHAPTER I.

NOSTALGO.

The flickering firelight fell upon the girl's pretty, thoughtful face; her violet eyes looked like deep lakes in it. She stood with one small foot tapping the polished brass rail of the fender. Claire Helmsley was accounted fortunate by her friends, for she was pretty and rich, and as popular as she was good-looking. The young man by her side, who stood looking moodily into the heart of the ship-log fire, was also popular and good-looking, but Jack Masefield was anything but rich. He had all the brain and all the daring ambition that makes for success, but he was poor and struggling yet, and the briefs that he dreamed of at the Bar had not come.

But he was not thinking of the Bar now as he stood by Claire Helmsley's side. They were both in evening dress, and obviously waiting for dinner. Jack's arm was around Claire's slender waist, and her head rested on his shoulder, so that by looking up she could just see the shadow on his clean-cut face. Though the pressure of his arm was strong and tender, he seemed as if he had forgotten all about the presence of the girl.

"Why so silent?" the girl said. "What are you thinking about, Jack?"

"Well, I was thinking about you, dearest," Jack replied. "About you and myself. Also of your guardian, Anstruther. I was wondering why he asks me so often and leaves us so much together when he has not the slightest intention of letting me marry you."

The girl colored slightly. The expression in her violet eyes was one of pain.

"You have never asked my guardian," she said . "We have been engaged now for over six months, Jack, and at your request I have kept the thing a dead secret. Why should we keep the matter a secret? You are certain to get on in your profession, and you would do no worse if the world knew that you had a rich wife. My guardian is kindness itself. He has never thwarted me in a single wish. He would not be likely to try and cross my life's happiness."

Jack Masefield made no reply for a moment. It was perhaps a singular prejudice on his part, but he did not like the brilliant and volatile Dr. Spencer Anstruther, who was Claire's guardian. He would have found it impossible to account for this feeling, but there it was.

"My guardian has plenty of money of his own," Claire said, as if reading his thoughts.

"There you are mistaken," Jack replied. "This is a fine old house, filled with beautiful old things. Anstruther goes everywhere; he is a favorite in the best society. Men of letters say he is one of the finest talkers in the world. But I happen to know that he has very little money, for a lawyer told me so. That being so, the £2,000 a year you pay him till you marry or come of age is decidedly a thing to take care of. On the whole, dearest, we had better go on as we are."

Claire had a smile for her lover's prejudices. Personally she saw nothing amiss with her guardian. She crossed over to the window, the blinds of which had not yet been drawn, and looked out. She looked across the old-fashioned garden in front of the house to the street beyond, where a few passengers straggled along. On the far side of the road stood an electric standard holding a flaring lamp aloft. The house opposite was being refaced, so that it was masked in a high scaffold.

As was the custom in London, the scaffolding had been let out to some enterprising bill-posting company. It was a mass of gaudy sheets and placards puffing a variety of different kinds of wares. In the centre, bordered by a deep band of black, was one solitary yellow face with dark hair and starting eyes. At the base was the single word "Nostalgo."

An extraordinary vivid and striking piece of work for a poster. The face was strong and yet evil, the eyes were full of a devilish malignity, yet there was a kind of laugh in them too. Artists spoke freely of the Nostalgo poster as a work of positive genius, yet nobody could name the author of it. Nobody knew what it meant, what it foreshadowed. For two months now the thing had been one of the sensations of London. The cheap Press had built up legends round that diabolically clever poster; the head had been dragged into a story. The firm who posted Nostalgo professed to know nothing as to its inner meaning. It had become a catchword; actors on the variety stage made jokes about it. But still that devilish yellow face stared down at London with the malignant smile in the starting eyes.

"Jack, they have put up a fresh 'Nostalgo' poster on the hoarding opposite," Claire said. "I wish they hadn't. That face frightens me. It reminds me of somebody."

"So it does me," Jack replied, with sudden boldness. "It reminds me of your guardian."

Claire smiled at the suggestion. The guardian was a large, florid man, well-groomed and exquisitely clean. And yet as Jack spoke the yellow face opposite seemed to change, and in some way the illusion was complete. It was only for an instant, and then the starting eyes and the queer smile that London knew so well were back again.

"You make me shudder," Claire said in a half-frightened way. "I should never have thought of that. But as you spoke the face seemed to change. I could see my guardian dimly behind it. Jack, am I suddenly growing nervous or fanciful? The thing is absurd."

"Not a bit of it," Jack said stoutly. "The likeness is there. It may be a weird caricature, but I can see it quite plainly. Don't you recall how Anstruther breaks out into yellow patches when he is excited or angry? I tell you I hate that man. I may be nonsensical, but—"

Jack paced up and down the room as if lost in thought. The light was shining on the face on the hoarding—it seemed to look at him with Spencer Anstruther's eyes.

"There is something wrong in this house," he said. "I feel it. You may laugh at me, you may say that I am talking nonsense, but there it is. The strange people who come here—"

"Sent by the police mainly. Don't forget that my guardian is one of the greatest criminologists of our time. There is no man in London who can trace the motive of a crime quicker than Mr. Anstruther. There was that marvelous case of those missing children, for instance—"

"Oh, I know," Jack said, with some suggestion of impatience in his voice. "And yet, if you don't mind, we will say nothing of our engagement at present."

Claire contested the point no longer. After all she was very happy as things stood. She had plenty of chances of meeting her lover, and Mr. Anstruther seemed to be altogether too wrapped up in his scientific studies to notice what was going on under his very eyes. He came into the room at the same moment humming a fragment of some popular opera.

There was nothing whatever about the man to justify Jack Masefield's opinions. Spencer Anstruther was calculated to attract attention anywhere. The man was tall and well set up, he had a fine commanding face softened by a tolerant and benign expression. People looked after him as he walked down the street and wondered which popular statesman he was. In society Anstruther was decidedly welcome, amongst men of learning he was a familiar figure. His scientific knowledge was great, certain publications of his were regarded in the light of text-books. Altogether he was a man to cultivate.

"I am afraid that I am late, young people," he said in a smooth, polished voice. "I hope you have been able to amuse yourselves together in my absence. You look moody, Jack. Don't those briefs come in as freely as you would like? Or have you been quarreling?"

"No, sir," Jack replied. "We never quarrel; we are too good friends for that. We have not the excuse in that way that lovers are supposed to possess."

"We have been studying that awful poster," Claire said. "I wish somebody would take it away. Jack is always seeing some likeness in it. He says that you—"

The girl paused in some confusion. Anstruther smiled as he put up his glasses.

"It is a complex face," he said. "Whose features does it remind you of just now, Jack?"

"Yours," Jack said boldly. He flashed the word out suddenly. Half to himself he wondered why he always felt a wild desire to quarrel with this man. "I hope you won't be offended, sir, but I can see a grotesque likeness to you in the famous repellent Nostalgo."

Claire looked up in some alarm. She was wondering how her guardian would take it. The log fire in the grate shot up suddenly and illuminated Anstruther's face. Perhaps it was the quick flare that played a trick on Claire's fancy, for it seemed to her that suddenly Anstruther's face was convulsed with rage. The benign pink expression had gone, the features were dark with passion, the fine speaking eyes grew black with malignant hatred. Claire could see the hands of the man clenched so hard that the knuckles stood out white as chalk. And there with it all was the likeness to Nostalgo that Jack had so boldly alluded to. The fire dropped and spurted again, and when it rose for the second time the face of Spencer Anstruther was smooth and smiling.

Claire passed her handkerchief across her eyes to concentrate the picture of fiendish passion that she had seen. Was it possible that imagination had played some trick on her? And yet the picture was as vivid as a landscape picked out and fixed upon the retina by a flash of lightning on a dark night. The girl turned away and hid her white face.

"I should like to meet the artist who drew that face," Anstruther said, with a smile. "One thing I am quite certain of—it is not the work of an Englishman. Well, it has found London something to talk about, and the advertisement is a very clever one. I dare say before long we shall discover that it is exploited in the interest of somebody's soap."

"I am inclined to favor the view that Nostalgo is something novel in the way of a thought-reader or a spiritualist," Jack said. "It seems to me—"

The dining-room door was thrown open by a woman servant, who announced that dinner was served. They passed across the hall into a large dark-walled room, the solitary light of which was afforded by a pair of handsome candelabra on the table. There were not many flowers, but they were all blood red, with a background of shiny, metallic green. The woman who waited passed from one plate to another without making the slightest sign. As she came into the rays of the shaded candles from time to time Jack glanced at her curiously. She was dressed in sombre, lustreless black, with no white showing at all. There was no cap on her head—nothing but a tangle of raven-black hair. Her brows were black and hairy, her skin as dark, so that her faded eyes were in striking contrast to her swarthy appearance. Her hands were very strong and capable, the mouth firm to the verge of cruelty. And yet there was something subdued, something beaten about the woman, as if she had been taken in a wild state and tamed. Anstruther seldom addressed an order to her in words; a motion of the hand, the raising

of an eyelid seemed to be sufficient for those pale, tired eyes, which somehow never for one instant relaxed their vigilance.

The woman was a mystery of the house; she seemed to be entirely dominated by her master's will. And yet there were strength and passion there, Jack felt certain. The fanatic only slumbered. A pansy fell from one of the flower vases, and Jack started out his hand to replace it.

"Did you ever see the evil face in the heart of a pansy blossom?" he asked, for there was a pause in the conversation. "It is a demon face—and familiar too. Miss Helmsley, whose face does this saffron heart of the pansy remind you of?"

Claire took the pansy from Jack's hand and studied it with a frown on her pretty face.

"Why, of course," she cried. "I see what you mean. It is Nostalgo, the man with the yellow face."

CHAPTER II.

THE CHOPIN NOCTURNE.

Claire gave the desired assurance, and rose from the table. She would have Jack's coffee saved for him in the drawing-room, she said. Anstruther lit a cigarette, and began to talk of crime. Crime and criminals had a fine fascination for him. Scotland Yard offered valuable inspiration for his new book on the criminal instinct, and in return he had been in a position to give the officials yonder one or two useful hints. The case he had on hand just now was a most fascinating one, but, of course, his lips were sealed for the present. Jack forgot his dislike in the fascination of the present.

"Stay here and finish your cigar," Anstruther said as he rose and pitched his cigarette into the fire. "I'll go into my study and work this thing out with the aid of my violin. I may be an hour or so, or I may be longer. If I have finished before eleven o'clock I'll come up with my fiddle, and we'll get Claire to play. If you require any more claret you can ring the bell."

Jack sat there for a time smoking and thinking matters over. Presently, from the study beyond, came the sound of music. Really, Anstruther was a wonderful man—he seemed able to do anything. He was not perhaps a great performer on the violin—his playing was a little too mechanical, and seemed to lack soul—but the execution was brilliant enough. Jack opened his cigarette case only to find that it was empty. There was a fresh supply in the pocket of his overcoat, which was hanging in the hall. He would be just in time for one more, and then he would join Claire in the drawing-room. The hall light had been turned low, so that, as Jack stood in the vestibule fumbling in his coat pocket, he was not visible, though he could see what was going on in the hall behind him.

There was a spot of light at the head of the staircase. Somebody was standing there looking down into the hall—somebody in a rough jacket buttoned to the throat and wearing a pair of rubber-soled shoes, for the intruder made not the slightest noise. Jack wondered if some impudent burglar was raiding the house at this hour. If so, he would get a warm reception presently. Jack stood there as the figure came down the stairs and turned along a corridor to the left of the drawing-room. But there was no challenge and no fight, for the simple reason that in the hall light, as the stranger passed, Jack recognized the face of Spencer Anstruther. There was no doubt about it; there was no possibility of a mistake here.

Inside the study the music once more began. Very gently Jack tried the handle of the door, but it was locked. Under ordinary circumstances this would have excited no suspicion; perhaps there was another way into the room by way of the corridor. But if so that did not explain why Anstruther was creeping about his own house in the semblance of a burglar, and wearing rubber-soled shoes. There was something creepy about the whole business. Jack returned to the vestibule again, and from there he passed into the garden. The study was at the side of the house, and a belt of shrubs outside afforded a pretty good cover. There was the study under with the blinds down and a strong light inside. Jack noted that it was a French window, a window frequently used, because the stone step outside had been worn by the pressing of many feet.

The smooth melody of Chopin was playing on inside. Jack stooped down to where he could see the lace flowers on the blind, and looked into the room. There was a little slit in the blind where the sun had worn it, and by this slit the whole of the room could be seen. The music had softened down to a piano passage taken very slowly. But Jack was not thinking of the music now at all, though the strains were soothing and flowing enough.

He rubbed his eyes to make sure that they did not deceive him. No, the room was plain enough, so was the sound of the music. And with it all the room was absolutely empty!

CHAPTER III.

THE MYSTERY OF THE STRINGS.

It was the most extraordinary thing in the world. Beyond question the room was absolutely empty. Jack could see to the far side; he noted the pictures and the flowers and the vases on the mantelpiece. His view was naturally narrowed by a small spyhole, but there was no portion of the room hidden from him, though he could not quite see the whole of it at one time.

The music was proceeding quite smoothly, though with pauses now and again. It was followed now and then by what sounded like subdued applause.

Jack stepped back from the window. He wanted to make certain that he had not mistaken the room. No, the sounds of music came from the study right enough. At the risk of being discovered he crept back into the house again and tried the study door. It was locked, and what was more, the key was in the lock, as the application of an eye testified.

And the music was proceeding quite swiftly again. The mystery was absolutely maddening. Jack wondered if there was some cabinet in the study hidden from view where the player had taken up his stand. At any rate somebody was playing Chopin's music—playing it very well. There was no magic about the thing.

The hall of the house was very quiet, nobody seemed to be about. Occasionally there came the sound of mirth from the servants' hall, but nothing more. Fully determined to get to the bottom of this mystery, Jack returned to the garden again. Once more his eye was glued to the slit in the blind. He could make nobody out in the room. There was little fear of his being detected, because a belt of shrubs hid the window from the road.

Without the slightest warning a figure appeared in the room. It was impossible to see where she came from, but of necessity she must have entered by the door. Jack was a little uncertain on that head, for his glance was not directed towards the door for the moment.

He saw the figure of a woman, young and exceedingly well dressed. She was wearing an evening gown of white satin that showed up the creamy pallor of her skin, for her neck and shoulders were bare. The neck was rather thin, Jack noted, and the shoulders more inclined to muscle than beauty. For a young girl it struck Jack that the upper part of her body looked old. But the face was dark and wholesome, and against the deep eyes and swarthy complexion the girl's hair was dazzling. It was beautiful, rippling hair, changing color as the light flashed upon it.

"Well, this is a bit of an adventure," the watcher told himself. "But where's the person in the room who let the young lady in? Somebody must have let her in, because the door was locked and the key on the inside. I saw it there, so I can swear to that fact. But who is she?"

There were many answers to the problem, for Spencer Anstruther was a man who had countless strange visitors. His vast knowledge of crime and the ramifications of human depravity brought him in contact with large numbers of people. Men and women in distress often came to him, and they came in increasing numbers since Anstruther had got the better of a gang of scoundrels in a recent famous blackmailing case. Sometimes these people came on their own initiative, sometimes they were sent by the police. But Anstruther never said anything about them. He looked upon himself as a confidential agent. Claire could have told of many curious visitors at all hours, though Anstruther never so much as alluded to them afterwards.

But this girl did not look in the least like anybody in trouble. Her dark features were almost expressionless; there was no display of violent emotions there. Her gaze slowly wandered round the room as if looking for something; she had much the aspect of a pupil whose attention is called to a blackboard by a master. As Jack watched, it seemed to him that he had seen this girl before. He could not recollect anybody in the least like her; that contrast of dark skin and fair hair was striking enough to impress itself upon the most careless mind, and yet Jack could not give the face a name. He could not permit himself to believe that he had made a mistake. He knew perfectly well that the expressionless features were quite familiar to him.