As soon as Dan had gone Tom blew out his light and slipped into the hallway.

This portion of the Inn was simple in design. A long corridor ran through the middle of the house to meet a similar passage at the southern end extending at right angles to the main hall. The South Chamber, occupied by the Marquis de Boisdhyver, opened into the southwest passage, but the door was well beyond the juncture of the two corridors. It was Pembroke's intention to conceal himself in the bedroom next the Marquis's chamber, from the door of which he could look down the entire length of the main hall, and by stepping outside get a view of the branch hallway into which the door of this room and that of the Marquis actually opened. A further advantage was that the windows of this room, like those of the South Chamber, looked out upon the Dunes and the Cove.

As Tom stepped from his chamber, the house seemed utterly deserted; save for the roaring of the wind without and an occasional creak or crack in the time-worn boards, there were no sounds.

The night was not a dark one, although the wind was rising and rain was threatening; for a full moon lurked behind the thick veil of cloud and something of its weird weak light relieved the darkness even of the great corridor of the Inn.

Tom stole softly down the hallway and gained the room next the Marquis's. He took his position in a great chair, which he drew near the open door, and laid his gun on the floor near at hand. No one could enter the hall without his seeing him. Every few moments he would tiptoe to the doorway, thrust his head into the corridor, and listen intently for any sound in the South Chamber.

It was a lonely and unpleasant vigil. The night was wild, the storm was rising, the old Inn was moaning as though in distress; and, despite his natural courage, fantastic terrors and dangers thrust themselves upon his excited imagination. He would much have preferred, he felt, to be out in the open as Dan was, even facing real dangers and greater difficulties. Deeper than by these imaginary fears of the night, he was racked with anxiety to know what had become of the girl he loved. Had she been decoyed away by the evil genius of the place; was she in danger? Had she disappeared of her own free will; and didn't she really love him?

He was not in the least sleepy; but after a while the vigil began to tell upon his nerves. He found it almost impossible to sit still and wait, perhaps in vain. He made innumerable trips across the room to the windows to look out into the bleak night. The landscape was blotted out. Not a light showed from the House on the Dunes; only the two lamps on the schooner at anchor in the Cove gleamed across the night. Eleven o'clock, twelve o'clock struck solemnly from the old clock on the stairs.

Once as he was looking out of the window, it seemed to him that the green light on the Southern Cross was moving. But it was impossible that she should weigh anchor in the teeth of the rising storm. He was mistaken. Nay, he was sure. But it was rising, slowly, steadily, as though drawn by an invisible hand, to about the height of the masthead. There at last it stopped, and swung to the wind, to and fro, to and fro; high above its red companion, high above the deck.

And then, suddenly, as if to answer this mysterious manoeuvre, the green light, that earlier in the evening had glowed from a north window of the House on the Dunes, now flashed from an east window of the old farmhouse; flashed, then gleamed steadily. The light on the Southern Cross was lowered slowly, then raised again. The light in the House on the Dunes vanished; soon flashed again and then vanished once more. Slowly the light in the schooner descended to its normal position. A moment later the green light appeared on the north side of the House on the Dunes, where it had been earlier, and shone there steadily.

Was it a signal to the Marquis de Boisdhyver? Tom tiptoed to the partition between his room and the South Chamber, and put his ear to the wall to listen. Not a sound reached him. He turned to the door to go into the corridor, and stood suddenly motionless. For there, advancing ever so cautiously down the hall, carrying a lighted candle in his hand, was the old Marquis. He was clad in night dress and cap, with a gayly-coloured dressing-gown worn over the white shirt. Slowly, silently, pausing every instant to listen; he stole on, gun in hand, and Tom followed him as cautiously and as quietly. Instead of turning to the right at the partition that divides the north and south wings of the Inn and going down stairs, the Marquis turned to the left, into the short hall that led directly to the great chamber occupied by Tom and Dan.

By the time Pembroke in pursuit had reached the turn and dared to peep around the corner of the wall, the Marquis was at the door of Dan's room. He stood there, ear bent close to the panel, intently listening.

Tom waited breathless. Not satisfied, Monsieur de Boisdhyver turned about and went into an adjoining chamber, the door of which stood open. Pembroke was about to advance, when the Marquis emerged again into the corridor, having left his lighted candle in the empty room. This manoeuvre, whatever advantage it had for the Marquis, was fortunate for Pembroke, for it left the end of the little hall, where he stood watching, in deep shadow. He could now step boldly from behind the concealing wall without fear of immediate detection.

Again the Marquis stood and listened at the door of Dan's room, then cautiously turned the knob. The door yielded and opened an inch or so. Monsieur de Boisdhyver put his ear to the crack. Dissatisfied with the absolute silence that must have met him, he pushed open the door a little further and thrust his head inside. In a moment he disappeared within.

Tom realized that the Marquis would soon discover the fact that the room was empty. He looked about quickly for a place of concealment that would command a view of all the halls. Fortunately the partition that divided the long corridor between the north and south wings was hung with heavy curtains. Deciding instantly, Pembroke slipped behind them, and ruthlessly slit an opening in the thick green stuff, through which he could peek out. He was just in time, as the Marquis came out of their bedroom and softly closed the door. He stood irresolute; then, with even greater caution, re-entered the room in which he had left his candle. To Tom's chagrin, the candle was suddenly extinguished and the Inn left in darkness.

For some moments, there was absolute silence. Then Tom could hear faintly,—or feel rather than hear—the Marquis cautiously finding his way back. Luckily, the old Frenchman was groping his way next the other wall. Pembroke slipped from behind the curtains and stole softly in pursuit. As he reached the south end of the corridor, he heard the latch of the Marquis's door click softly. Alarmed by discovering that they were not in bed, thought Tom, he had abandoned whatever purpose he had in mind for his midnight prowl.

After waiting a little and hearing no more, Tom went again to the window. The rain had begun now and the wind was blowing a gale. Suddenly Pembroke discerned a light shining from the window next the very one from which he was peering into the darkness,—the steady glow of a deep red light.

"Another signal!" he murmured; then waited to see if it would be answered by the House on the Dunes. Perhaps fifteen minutes passed, and then, suddenly, there gleamed through the rain and dark, a tiny bit of red flame, just where the House on the Dunes must be. A little later the red lamp on the Southern Cross performed a fantastic ascension to what Pembroke took to be the masthead.

The red light in the neighbouring window was extinguished. Almost instantly the red spark on the Dunes disappeared, and in a few moments the schooner's lamp began its descent. Simultaneously they glowed again and the ship's light danced upward; then the two red lights on shore vanished and the lamp on the Southern Cross sank to its proper place and stayed there.

Of one thing Tom was sure: The Marquis, the lady at the House on the Dunes, and the skipper of the schooner in the Cove, were in collusion. Of another thing he felt almost equally certain: the red light was a signal of danger, and the message of danger flashed across the night was the fact that he and Dan were not safe asleep in bed.

For a long time he watched, keen with excitement; listened patiently; started at every sound. But nothing more unusual did he hear that night than the roar of the wind, the dash of the brawling southeaster against the panes, and the groans of the old house, shaken by the storm. Toward morning he crept back to bed and fell instantly into a deep and dreamless sleep.

While Tom was thus watching and sleeping a somewhat different experience had fallen to the lot of Dan Frost. He had no definite plan in making a midnight visit to the vicinity of the House on the Dunes, but he hoped to discover some clue to the surrounding mysteries. From time to time during the day he had taken his field glasses to one of the upper rooms of the Inn, and scanned the countryside but nothing unusual seemed astir in the white world without. The Southern Cross had lain on the surface of the little cove all day, swaying with wind and tide, no sign of activity upon her decks. It was after ten when he started forth. The night was not quite dark, for the full moon was shining somewhere behind the thick veil of clouds. Earlier in the evening Dan had intended to go boldly to the House itself and demand an interview with old Mrs. Meath; but he reflected that he would probably be met with the excuse that Mrs. Meath was ill, and he did not know how he could force himself in, particularly past the barrier of Madame de la Fontaine's charming manner.

It was an unpleasant walk with the wind in his face, and it was nearly eleven before he turned into the long dune road, which branched from the Port Road near the Rocking Stone and led directly to the old farmhouse on Strathsey Neck. To his chagrin it appeared that all lights had been extinguished as if the inmates of the house had gone to bed.

The old farmhouse loomed before him, dark and forbidding. On either side there were outhouses, and in the rear quite near the house a barn. There was not a tree on the place; indeed, there was little vegetation upon the entire Neck, save the grass of the middle meadows which in summer furnished scant nourishment for the cattle and a flock of sheep. Now all was bleak and covered with snow, and a freshening gale swept out of the great maw of the Atlantic.

Keeping close to the fence, Frost began to make a complete circuit of the farmhouse. As he turned a corner of the south end, or rear of the house, he was relieved to see a light burning in the kitchen. He stole cautiously to a position within the shadow of the barn from which he could get a glimpse of the interior. In the kitchen standing before a deal table, he saw a young woman—not Jane, Mrs. Heath's maid-of-all-work, but a stranger,—with her hands deep in a bowl of dough. Her back was toward him, but he guessed that she was Madame de la Fontaine's maid, whom he had seen in the morning. The door into the dining-room beyond stood open, and by craning his neck, Dan could see that the room was lighter, but he could not discover whether or not it were occupied. The shutters of the dining-room were so closely barred and the curtains so tightly drawn that not a ray of light penetrated to the outside.

The girl in the kitchen proceeded busily about her work. She was evidently engaged, despite the lateness of the hour, in mixing bread.

Once while he waited patiently, to what end he hardly knew, Madame de la Fontaine entered the kitchen. She was clad in black and held in her hands what Dan took to be a ship's lamp. She stood for a moment in the doorway and spoke to the servant maid. The girl stopped her work, and taking a strip of paper, ignited it at a candle and lighted the lamp, which Madame de la Fontaine held up for her. It glowed instantly with a deep green flame, such as Tom had described as shining from a window of the House on the Dunes in the early evening.

As soon as her lamp was lighted Madame de la Fontaine left the room. Supposing that she was about to give a signal, Dan's heart leaped at the prospect of some result to his eavesdropping, and he stole carefully around to the front of the house. Presently from an upper window in the east side of the house, not the north as he had expected, he saw the green light sending forth its message across the Dunes—to whom? Probably the signal could be seen from the Inn, but it more likely was intended for the schooner in the Cove. Sure enough, as he watched, Dan saw the phenomenon of the ascending lamp on the Southern Cross, which at that identical moment Tom Pembroke was watching from his post of vantage in one of the south windows of the Inn.

A little later the signal was removed from the east window of the farmhouse and placed in a north window. Dan looked to see the answering gleam from the Inn at the Red Oak. But none came. Crouched in a corner of the fence, he waited perhaps for half-an-hour.

Suddenly a signal gleamed from the Inn, but this time it was not green as he expected, but red. In a few moments a form appeared in the window of the farmhouse, and a white hand, which he supposed was that of Madame de la Fontaine, took hold of the lamp and reversed it, so that now it showed red. The light in the Inn vanished, reappeared, vanished again. The same thing happened to the light in the House on the Dunes. And looking eastward, Dan saw the ship's red lamp perform its fantastic ascent and descent. Soon all was left in darkness. Frost slipped back to his post near the barn and looked again into the kitchen.

Madame de la Fontaine was standing in the doorway as before. The maid, turning away from the table, came at that moment to the window, and raised the sash, as though she were overheated. Presently, leaving the window open, she turned to her mistress, and Dan could hear the sharp staccato of her voice as she said something in what seemed to him her barbarous French.

Impelled by curiosity, he crept closer to the house. He was within six feet of the window, standing on the tip of his toes. Suddenly he felt himself pinioned from behind; his arms were gripped as in a vise, a hand grasped his throat and began to choke him, and a sharp knee was planted with terrific force in the small of his back. He made a gurgling sound as he went backward, but there was no opportunity for struggling. He recovered from the shock to find himself stretched at full length in the wet snow. Some one was sitting upon him, struggling to thrust a gag into his mouth; some one else was binding his hands and feet.

He could just distinguish, in the sickly moonlight and the dim rays of the candle from the kitchen, the faces of his assailants. One was the murderous looking Frenchman, the skipper of the Southern Cross, the other he took to be a common seaman.

Attracted by the scuffle, the French maid had thrust her head out of the window and was addressing the combatants in vigorous French. Neither then nor later did Madame de la Fontaine appear. When Frost was safely bound and gagged, Captain Bonhomme arose, said a few words to his companion, and disappeared into the farmhouse. Dan's guard searched him rapidly, confiscated his revolver and knife, and then resumed his seat upon his legs. Inside the kitchen Dan could hear the sounds of an animated French dialogue, in which he imagined from time to time that he detected the silvery tones of Madame de la Fontaine's voice. Perhaps fifteen minutes elapsed. Captain Bonhomme came out of the house, strode to the spot where Dan was lying, and addressed him in excellent English.

"Monsieur; for purposes which it is superfluous to explain, it is decided to extend to you for a while the hospitality of my good ship the Southern Cross—a hospitality, I may say, that your unceremonious eavesdropping has thrust upon you. I will release your feet; and then, monsieur, you follow my good Jean across the sands. If you are quiet, no harm shall come to you. If you resist, cher monsieur, it will be of painful duty that I entrust the contents of this revolver into—mais non! Vous comprenez, n'est-ce pas?—Bien!"

He gave a sharp order to the seaman. The handkerchief about Dan's ankles was untied, and he was roughly assisted to his feet.

"The snow is wet, eh! Yes, for the good wind is moist. Now, Allons!"

Jean led the way, and Dan, deciding that he had no choice in the matter, followed obediently. The captain brought up the rear. As they went out through the gate, Dan turned for a moment and looked back at the house. He could see the French maid still at the kitchen window. At the same moment Captain Bonhomme glanced back and ceremoniously raised his hat.

"Bonsoir, mam'zelle."

"Bonsoir, monsieur," was the sharp reply, and the window was lowered with a bang.

They went on in silence across the Dunes to the beach. There, drawn up above high water line, they found a skiff. The captain and Jean shoved off, sprang in, and the little boat plunged into the combing waves. They reached the Southern Cross without misadventure. The captain blew a call upon a boatswain's whistle. A rope was lowered and Jean made the skiff fast to the ladder at the schooner's side. The captain took out his revolver and held it in his hand, while Jean unloosed the cords that bound Dan's wrists.

"Now up, mon ami."

For a moment Dan thought of risking a scuffle in the unsteady skiff, but discretion proved the better part of valour, and he climbed obediently on to the deck. The seaman stood close by till the captain and Jean had clambered up after him. A few words in French to his men, then Captain Bonhomme, beckoning to Dan to follow, led the way down the companion. He opened the door of a little cabin amidships and bade Frost enter.

"You will find everything required for your comfort, monsieur," he said, "and I trust you will make yourself at home, as you say; and enjoy a good night and a sound sleep. We can discuss our affairs in the morning."

And with the words, he closed the door, turned the key in the lock, and left Dan to his reflections.