In the morning the fog lifted, a bright sun shone from a cloudless sky, the marshes sparkled with pools of melted snow and the long-promised thaw seemed definitely to have set in. Soon after breakfast Tom sent Jesse to the Red Farm with directions for the people there to make preparations for Mrs. Frost and Nancy, whom he proposed to drive over himself in the course of the afternoon.

About the middle of the morning as Tom and Nancy stood on the gallery discussing the situation, Tom drew her attention to a small boat putting off from The Southern Cross. They examined it through the glass, and Nancy recognized the figure of Captain Bonhomme sitting amongst the stern-sheets.

"You may depend upon it," said Tom, "he is going to the House on the Dunes to report your disappearance to Madame de la Fontaine. The most curious thing about this whole business to me is the mixing-up in it of such a woman as Dan described Madame de la Fontaine to be."

"It is strange," Nancy agreed, "but from the bits of talk I've overheard, I should say that she was the prime mover in it all."

"In a way I am rather glad of that," said Tom, "for with a woman at the head of things there is less chance of their resorting to force to gain their ends. But the stake they are playing for must be a big one, and already they have done enough to make me sure that we should be prepared for anything. I shall be surprised if we don't get some communication from them to-day. The old Marquis counts on it, or he would not keep so still. At any cost, we must get Dan back."

They talked for some time longer and were about to go in, when Nancy pointed to a horse and rider coming down the avenue of Maples. A glance sufficed to show that the rider was a woman. Nancy slipped inside to escape observation, while Tom waited on the gallery to receive the visitor.

As the lady drew rein under the Red Oak, he ran down the steps, and helped her to dismount. Her grace, her beauty, her manner as of the great world, made him sure that he was in the presence of Madame de la Fontaine.

"Good morning, sir," said the lady, with a charming smile, "if I mistake not, I have the pleasure of addressing Mr. Pembroke?"

"Yes, madam,—at you service," replied Tom.

"I am come on a strange errand, monsieur; as an ambassadress, so to say, of those whom I fear you take to be your enemies."

"You are frank, madam. I believe that I am speaking with—?"

"Madame de la Fontaine," the lady instantly supplied. "Events have so precipitated themselves, monsieur, that pretense and conventionality were an affectation. I am informed, you understand, of your brilliant rescue of Mademoiselle Eloise de Boisdhyver."

"If you mean Nancy Frost by Mademoiselle Eloise de Boisdhyver, madam, your information is correct. I gathered that you had been told of this, when I saw Captain Bonhomme make his way to the House on the Dunes this morning."

"Ah! What eyes, monsieur!" exclaimed the lady. "But I have grown accustomed to having my privacy examined over-curiously during the few days I have spent on your hospitable shores. Mais pardon—my purpose in coming to the Inn at the Red Oak this morning was but to request that my name be conveyed to Monsieur the Marquis de Boisdhyver."

"You mean, madam, that you wish to see the Marquis?"

"Yes, monsieur, if you will be so good as to allow me to do so."

"I am sorry," Tom rejoined, "that I must disappoint you. Circumstances over which the Marquis has no control will deprive him of the pleasure of seeing you this morning."

"Ah!" exclaimed Madame de la Fontaine, "I was right then. Monsieur le Marquis is, shall we say, in confinement?"

"As you please, madam; as safe, for the time, as is my friend Dan Frost."

"Eh bien, monsieur! It is that you have—do you not say?—turned the tables upon us?"

"Precisely, madam," assented Tom.

"And you will not permit me even a word—ever so little a word—with my poor friend?" murmured Madame de la Fontaine plaintively.

"Again I am sorry to refuse you, madam; but—not even a little word."

"So! Mais oui, I am not greatly surprised. I was assured last night...."

"When you did not see the signals?" suggested Tom quickly.

"When I did not see the signals," repeated the lady, with a glance of the briefest enquiry, "I was assured that something had befallen Monsieur le Marquis. Mais vraiment, monsieur, you do us much dishonour in assuming a wicked conspiracy on our parts. The Marquis is my friend; he is also the friend of the charming Mademoiselle. All that we wish, all that we would do is as much in her interest as in his own. But it is impossible that my old friend shall remain in confinement. On what condition, monsieur, will you release the Marquis de Boisdhyver?"

"On the condition, naturally, that my friend Dan Frost is released from the Southern Cross."

"Ah! Is it that you are quite sure that Monsieur Frost is confined on the ship?"

"Quite sure, Madame de la Fontaine. I was on board The Southern Cross last night."

"Yes, I know it; and I congratulate you upon your extraordinary success. Very well, then, I accept your condition. Monsieur Dan Frost returns; Monsieur le Marquis is released. And now you will perhaps have the kindness—"

"No, madame; in this affair the Marquis and his friends have been the aggressors. I cannot consent that you should hold any communication with the Marquis till Dan returns free and unharmed to the Inn."

"And what assurance then shall I have that the Marquis will be released?"

"None, madame, but my word of honour."

"Pardon, monsieur. I accept your terms. Monsieur Frost shall return. The instant he enters the Inn at the Red Oak, you promise that the Marquis de Boisdhyver be released and that he be given this note from me?"

"Certainly, madam."

The lady took a sealed note from the pocket of her habit and handed it to Tom. "There remains, monsieur," she murmured, "but to bid you good-day. If you will be so kind—"

She ran lightly down the steps, and held up her foot for Tom to assist her into the saddle.

"Your friend will return tout de suite, monsieur," she cried gayly, as she drew in the rein.

"And we shall have the pleasure of seeing you again?" asked Tom.

"Ah! who can tell?" She touched the horse lightly with her whip, inclined her head, and soon disappeared down the avenue of maples.

Some time later Nancy and Tom watched her cantering across the beach. She waved her handkerchief as a signal to the schooner; a small boat put ashore, and she was rowed out to The Southern Cross.

"Once Dan is back, and we get rid of the old Marquis," said Tom, "I shall breathe considerably easier."

"I can't believe they will give the game up so easily," was Nancy's reply. "Seizing the Marquis, Tom, was a check, not a mate."

Out on the schooner in the Cove, Madame de la Fontaine and Dan Frost were once more talking together.

"Dear boy," said the lady. "I cannot do that which I promised. It is impossible that your sister shall make to you the request to give me the torn scrap of paper, for the reason that Mademoiselle Nancy has chosen to disappear. Have no fear, monsieur, for I have good reason to believe she has returned to the Inn at the Red Oak. Our schemes, mon ami, have failed. You are no longer a prisoner, you are free. And this is good-bye. I abandon our mission. I leave the House on the Dunes to-day; to-morrow I return to France."

"But, madame, you bewilder me," exclaimed Dan. "Why should you go; why should we not all join forces, hunt for the treasure together, if there is a treasure; why this division of interests?"

"C'est impossible!" she exclaimed impetuously. "Monsieur le Marquis will not consent. He is treated with intolerable rudeness by your friend Mr. Pembroke. He will not accept that which I propose. And I—vraiment, I desire no longer to work against you. No, monsieur Dan, tout est fini, we must say good-bye."

She held out her hands and Dan impetuously seized them. Then, suddenly, she was in his arms and his lips were seeking hers.

"I cannot let you go," he cried hoarsely. "I cannot say good-bye."

For a moment he held her, but soon, almost brusquely, she repulsed him. "C'est folie, mon ami, folie! We lose our heads, we lose our hearts."

"But I love you," cried Dan. "You must believe it; will you believe it if I give you the paper?"

"No, no!—What!—you wish to give to me the secret of the Oak Parlour?—"

"Aye, to entrust to you my life, my soul, my honour."

"Ah, but you must go," she murmured tensely.

"Captain Bonhomme is returning. It is better that he knows of your release after you are gone. C'est vrai, my friend, that I risk not a little in your behalf. Go now, quickly ... No! No!" she protested, as she drew away from him. "I tell you, C'est folie,—madness and folly. You do not know me. Go now, while there is time!"

"But you will see me again?" insisted Dan. "Promise me that; or, on my honour, I refuse to leave. Do with me what you will, but—"

"Listen!" she whispered hurriedly. "I shall meet you to-night at ten o'clock, at the end of the avenue of maples near to your inn; you know the place? Bien! Bring me the paper there, to prove that you trust me. And I—mais non, I implore you—go quickly!"

Dan turned at last and opened the door. Madame de la Fontaine called sharply to the waiting Jean, and he, motioning to Dan to follow him, led the way on deck. In a moment they were in a little boat heading for the shore. The afternoon sun was bright in the western sky. The Southern Cross rode serenely at anchor, and from her deck, Madame de la Fontaine was waving him good-bye.