Corinne did not reappear for nearly a week. During all that time the twins, who only saw her in school, reported that she would have nothing to say to them outside of this statement:

"Let me alone, girls, just for a while. I'm working hard at it. When I've run to earth something worth while, I'll tell you, and we'll have another meeting!" And that was absolutely all they could get from her.

Meanwhile, Margaret was passing the slow days in a fever of impatience and baffled expectation. Now that she no longer had her mind occupied by puzzling out the curious old journal and could only sit and wait for the results of Corinne's work, she grew terribly restless. So much so, indeed, that the lynx-eyed Sarah, who watched her beloved charge like a cat, made up her mind that Margaret was beginning to have symptoms of a real fever. She prepared, therefore, a huge bowl of boneset tea to be taken in instalments.

Now, if there was any one thing under the sun that Margaret hated more than another, it was boneset tea! And, moreover, in this case she knew that there was absolutely no need of the remedy. But this she dared not confide to Sarah lest she awaken fresh suspicion in that handmaiden's already too suspicious mind. So she swallowed her bitter doses uncomplainingly, and longed for Corinne's coming for more reasons than one!

And then at last, six days later, Corinne came flying home with the twins one afternoon, and all three burst in unexpectedly on the delighted Margaret. Corinne was armed with a load of volumes that were plainly not school-books, and these she planked down on the floor beside the invalid-chair with just one brief remark:

"I've got it!"

Questions and inquiries were hurled at her thick and fast, but not one of them would she answer till all were seated about Margaret's chair in the usual half-circle by the open fire. Then she began quietly, but with much suppressed excitement in her voice:

"Yes, girls, I've got it—at last! I'm going to tell you all about it, and you're going to have the surprise of your lives! It took me a long while before I struck just the right clue. I've spent about every afternoon reading at the library near us. I even went up to the big one at Forty-second Street yesterday. And every evening at home has found me still digging at it. I've neglected my school work completely, and have failed in everything this week; but I don't care!

"Margaret's a trump! She put us all on the right track in the first place by sensibly suggesting the Revolution. That was fine! But, of course, the subject was a big one and concerned the whole thirteen original colonies. In thinking it over, I decided that since Alison came from Bermuda, the 'city' she keeps speaking of would most likely be the nearest one to Bermuda. On looking it up, I found the nearest was Charleston, South Carolina. So I started in and hunted up every bit of Revolutionary history I could find about Charleston, but never a thing did I strike that helped a bit.

"Then I gave that up and tried another city. As there didn't seem to be any very likely places south of Charleston, I turned north and tried Richmond, Baltimore and Philadelphia. Not a single thing in any one of them that threw a ray of light on our troubles! Finally, I began on New York—and hit it right away!" Her listeners gave a little jump. "Yes, right here in old New York. And come to think of it, that was the most likely place, after all, and I might have saved myself all that other bother, if only I'd used a little common sense!"

"But how did you know right away that it was New York?" demanded Margaret.

"Why, the simplest thing in the world! Almost the first thing I came across, in reading up about New York during the Revolution, was about a place called—Richmond Hill!"

"What? Where?" they all cried in one breath.

"Yes, Richmond Hill! It was the name of a big mansion and estate outside of the city, and was a very famous place in its time."

"But how did you know it had anything to do with Alison?" they demanded incredulously.

"Well, just about twenty things pointed to it without a doubt. I'll tell you all about it. In the first place, I read that this mansion was built in 1760 by the paymaster-general of the British army, and his name was—Abraham Mortier!"

She stopped significantly, but no one seemed to catch her meaning till Margaret suddenly cried:

"Madame M.!"

"Precisely!" said Corinne. "I wondered if you'd catch it. 'Madame M.' must have been Madame Mortier, his wife, of course!"

"But Alison didn't say anything about Abraham Mortier," objected Bess.

"That's just it,—she didn't, because Madame Mortier was then a widow. Her husband died quite suddenly, just at the outbreak of the war. So that's accounted for. And don't you remember that Alison said Madame M. allowed the steward to transact all the business of the household. She wouldn't be doing that if her husband were alive! Well, except for that, I couldn't find out another thing about the Mortiers. History doesn't mention them again. But it tells a lot about other things we're interested in. To begin with, after the siege of Boston, Washington came to New York, and was there several months. Now then, while he was in the city, he made his headquarters at—Richmond Hill! What does that suggest to you?"

Again they all looked blank for a moment, and once more Margaret was first to catch the idea.

"I've got it! Washington is the 'he' that Alison says so much about but never names!"

"Right!" cried Corinne.

"How do you know?" clamored the less astute twins.

"This way," explained Corinne, "Everything that Alison says about 'him' tallies with the descriptions of Washington—'grave, courteous, stately, kindly, thoughtful.' There isn't a shadow of doubt! She speaks of his servants and men and guards. Only a commander-in-chief would be likely to have all that retinue."

Suddenly Jess, who had been deep in thought, interrupted: "But, see here! If it was Washington, why did Madame M. act so hateful about him? Alison said if she hadn't been sick, she'd have gladly slammed the door in his face. I don't understand it!"

"Oh, that's easy! Madame Mortier was, without doubt, a Tory! You know, New York was full of Tories at the time, and they hated Washington and all the rebels like—like poison!"

"But I still don't understand," insisted Jess, "how, if Madame Mortier was a Tory and hated Washington so, he should come to be using her house for his headquarters. I don't wonder she was furious!"

"I thought of that too," said Corinne, "and it seemed strange to me; but, from what I've read, I think it was this way: he had to have his headquarters somewhere while he was in New York, and just at first he had them way down in the lower part of the city, in the Kennedy house. But later he wanted to get outside of the city for some reason; perhaps it was on account of one of those plagues of smallpox or yellow fever that were always breaking out there. Then, of course, there were so few houses outside that he had to take anything he could find that was suitable. So he chose Richmond Hill, and Lady Washington followed him there later."

"How do you know?" again demanded the ever-skeptical listeners.

"Well, didn't Alison say, just toward the last, that 'his lady' had come?"

"True enough!" assented Jess. "And that makes me think of something else. Was that the 'Lady Blank' she spoke of first, do you think?"

"Without doubt, for she even says, 'I do not think she remembers me.' But where or how she met her before, I haven't had time to work out. Anyhow, it explains why Madame Mortier began to be suspicious of Alison. Of course she would be if she was such a staunch Tory and found Alison talking to the wife of her worst enemy!

"But here's something very important, and it's the real proof of the whole thing. The rest was just rather easy guesswork. Do you know, while Washington was at Richmond Hill, that summer of 1776, the Tories in the city got up a big plot to kill him, blow up his fortifications, massacre all his soldiers, and spoil everything for the Americans? And—it very nearly was accomplished, only some one discovered it and gave the whole thing away. That's the plot, evidently, which was brewing when Alison felt that something strange and mysterious was going on. And here's my positive proof: one of the chief conspirators in the plot was a man who kept a tavern near the edge of the woods close to Washington's headquarters, and his name was—Corbie!"

"Didn't we say that name would be of great help?" cried Margaret, excitedly. "Why, all this seems like a fairy story coming true! Is there anything else, Corinne?"

"Yes, there's one other thing. But before I tell you, I'm curious to know why you haven't asked one question."

"What?"

"Why, the exact location of Richmond Hill. You haven't exhibited the least curiosity about that!"

"But you said it was outside of the city somewhere," put in Bess, "and I suppose it was up around Fordham or West Farms, or even White Plains. It must have been pretty far out."

Corinne laughed. "Do you realize that the 'city' only extended to about City Hall Park in those days? And all beyond that was out in the country! No, Richmond Hill was right here in Greenwich Village!"

They all stared at her in such frank amazement that she broke into a giggle.

"Perhaps you think that's rather astonishing, but I've something to say that's even more so. I told you I'd give you the surprise of your lives, and here it is: the exact spot where the Richmond Hill mansion stood was—just about where this house stands now!"