HE next day passed slowly. It was necessary to curtail expenditure. Carefully husbanded, forty pounds will last a long time. Luckily the weather was fine, and "walking is cheap," dictated Tuppence. An outlying picture house provided them with recreation for the evening.

The day of disillusionment had been a Wednesday. On Thursday the advertisement had duly appeared. On Friday letters might be expected to arrive at Tommy's rooms.

He had been bound by an honourable promise not to open any such letters if they did arrive, but to repair to the National Gallery, where his colleague would meet him at ten o'clock.

Tuppence was first at the rendezvous. She ensconced herself on a red velvet seat, and gazed at the Turners with unseeing eyes until she saw the familiar figure enter the room.

"Well?"

"Well," returned Mr. Beresford provokingly. "Which is your favourite picture?"

"Don't be a wretch. Aren't there ANY answers?"

Tommy shook his head with a deep and somewhat overacted melancholy.

"I didn't want to disappoint you, old thing, by telling you right off. It's too bad. Good money wasted." He sighed. "Still, there it is. The advertisement has appeared, and—there are only two answers!"

"Tommy, you devil!" almost screamed Tuppence. "Give them to me. How could you be so mean!"

"Your language, Tuppence, your language! They're very particular at the National Gallery. Government show, you know. And do remember, as I have pointed out to you before, that as a clergyman's daughter——"

"I ought to be on the stage!" finished Tuppence with a snap.

"That is not what I intended to say. But if you are sure that you have enjoyed to the full the reaction of joy after despair with which I have kindly provided you free of charge, let us get down to our mail, as the saying goes."

Tuppence snatched the two precious envelopes from him unceremoniously, and scrutinized them carefully.

"Thick paper, this one. It looks rich. We'll keep it to the last and open the other first."

"Right you are. One, two, three, go!"

Tuppence's little thumb ripped open the envelope, and she extracted the contents.

"DEAR SIR,

"Referring to your advertisement in this morning's paper, I may be able to be of some use to you. Perhaps you could call and see me at the above address at eleven o'clock to-morrow morning.

"Yours truly,

"A. CARTER."

"27 Carshalton Gardens," said Tuppence, referring to the address. "That's Gloucester Road way. Plenty of time to get there if we tube."

"The following," said Tommy, "is the plan of campaign. It is my turn to assume the offensive. Ushered into the presence of Mr. Carter, he and I wish each other good morning as is customary. He then says: 'Please take a seat, Mr.—er?' To which I reply promptly and significantly: 'Edward Whittington!' whereupon Mr. Carter turns purple in the face and gasps out: 'How much?' Pocketing the usual fee of fifty pounds, I rejoin you in the road outside, and we proceed to the next address and repeat the performance."

"Don't be absurd, Tommy. Now for the other letter. Oh, this is from the Ritz!"

"A hundred pounds instead of fifty!"

"I'll read it:

"DEAR SIR,

"Re your advertisement, I should be glad if you would call round somewhere about lunch-time.

"Yours truly,

"JULIUS P. HERSHEIMMER."

"Ha!" said Tommy. "Do I smell a Boche? Or only an American millionaire of unfortunate ancestry? At all events we'll call at lunch-time. It's a good time—frequently leads to free food for two."

Tuppence nodded assent.

"Now for Carter. We'll have to hurry."

Carshalton Terrace proved to be an unimpeachable row of what Tuppence called "ladylike looking houses." They rang the bell at No. 27, and a neat maid answered the door. She looked so respectable that Tuppence's heart sank. Upon Tommy's request for Mr. Carter, she showed them into a small study on the ground floor where she left them. Hardly a minute elapsed, however, before the door opened, and a tall man with a lean hawklike face and a tired manner entered the room.

"Mr. Y. A.?" he said, and smiled. His smile was distinctly attractive. "Do sit down, both of you."

They obeyed. He himself took a chair opposite to Tuppence and smiled at her encouragingly. There was something in the quality of his smile that made the girl's usual readiness desert her.

As he did not seem inclined to open the conversation, Tuppence was forced to begin.

"We wanted to know—that is, would you be so kind as to tell us anything you know about Jane Finn?"

"Jane Finn? Ah!" Mr. Carter appeared to reflect. "Well, the question is, what do you know about her?"

Tuppence drew herself up.

"I don't see that that's got anything to do with it."

"No? But it has, you know, really it has." He smiled again in his tired way, and continued reflectively. "So that brings us down to it again. What do you know about Jane Finn?

"Come now," he continued, as Tuppence remained silent. "You must know SOMETHING to have advertised as you did?" He leaned forward a little, his weary voice held a hint of persuasiveness. "Suppose you tell me..."

There was something very magnetic about Mr. Carter's personality. Tuppence seemed to shake herself free of it with an effort, as she said:

"We couldn't do that, could we, Tommy?"

But to her surprise, her companion did not back her up. His eyes were fixed on Mr. Carter, and his tone when he spoke held an unusual note of deference.

"I dare say the little we know won't be any good to you, sir. But such as it is, you're welcome to it."

"Tommy!" cried out Tuppence in surprise.

Mr. Carter slewed round in his chair. His eyes asked a question.

Tommy nodded.

"Yes, sir, I recognized you at once. Saw you in France when I was with the Intelligence. As soon as you came into the room, I knew——"

Mr. Carter held up his hand.

"No names, please. I'm known as Mr. Carter here. It's my cousin's house, by the way. She's willing to lend it to me sometimes when it's a case of working on strictly unofficial lines. Well, now"—he looked from one to the other—"who's going to tell me the story?"

"Fire ahead, Tuppence," directed Tommy. "It's your yarn."

"Yes, little lady, out with it."

And obediently Tuppence did out with it, telling the whole story from the forming of the Young Adventurers, Ltd., downwards.

Mr. Carter listened in silence with a resumption of his tired manner. Now and then he passed his hand across his lips as though to hide a smile. When she had finished he nodded gravely.

"Not much. But suggestive. Quite suggestive. If you'll excuse my saying so, you're a curious young couple. I don't know—you might succeed where others have failed... I believe in luck, you know—always have...."

He paused a moment, and then went on.

"Well, how about it? You're out for adventure. How would you like to work for me? All quite unofficial, you know. Expenses paid, and a moderate screw?"

Tuppence gazed at him, her lips parted, her eyes growing wider and wider.

"What should we have to do?" she breathed.

Mr. Carter smiled.

"Just go on with what you're doing now. FIND JANE FINN."

"Yes, but—who IS Jane Finn?"

Mr. Carter nodded gravely.

"Yes, you're entitled to know that, I think."

He leaned back in his chair, crossed his legs, brought the tips of his fingers together, and began in a low monotone:

"Secret diplomacy (which, by the way, is nearly always bad policy!) does not concern you. It will be sufficient to say that in the early days of 1915 a certain document came into being. It was the draft of a secret agreement—treaty—call it what you like. It was drawn up ready for signature by the various representatives, and drawn up in America—at that time a neutral country. It was dispatched to England by a special messenger selected for that purpose, a young fellow called Danvers. It was hoped that the whole affair had been kept so secret that nothing would have leaked out. That kind of hope is usually disappointed. Somebody always talks!

"Danvers sailed for England on the Lusitania. He carried the precious papers in an oilskin packet which he wore next his skin. It was on that particular voyage that the Lusitania was torpedoed and sunk. Danvers was among the list of those missing. Eventually his body was washed ashore, and identified beyond any possible doubt. But the oilskin packet was missing!

"The question was, had it been taken from him, or had he himself passed it on into another's keeping? There were a few incidents that strengthened the possibility of the latter theory. After the torpedo struck the ship, in the few moments during the launching of the boats, Danvers was seen speaking to a young American girl. No one actually saw him pass anything to her, but he might have done so. It seems to me quite likely that he entrusted the papers to this girl, believing that she, as a woman, had a greater chance of bringing them safely to shore.

"But if so, where was the girl, and what had she done with the papers? By later advice from America it seemed likely that Danvers had been closely shadowed on the way over. Was this girl in league with his enemies? Or had she, in her turn, been shadowed and either tricked or forced into handing over the precious packet?

"We set to work to trace her out. It proved unexpectedly difficult. Her name was Jane Finn, and it duly appeared among the list of the survivors, but the girl herself seemed to have vanished completely. Inquiries into her antecedents did little to help us. She was an orphan, and had been what we should call over here a pupil teacher in a small school out West. Her passport had been made out for Paris, where she was going to join the staff of a hospital. She had offered her services voluntarily, and after some correspondence they had been accepted. Having seen her name in the list of the saved from the Lusitania, the staff of the hospital were naturally very surprised at her not arriving to take up her billet, and at not hearing from her in any way.

"Well, every effort was made to trace the young lady—but all in vain. We tracked her across Ireland, but nothing could be heard of her after she set foot in England. No use was made of the draft treaty—as might very easily have been done—and we therefore came to the conclusion that Danvers had, after all, destroyed it. The war entered on another phase, the diplomatic aspect changed accordingly, and the treaty was never redrafted. Rumours as to its existence were emphatically denied. The disappearance of Jane Finn was forgotten and the whole affair was lost in oblivion."

Mr. Carter paused, and Tuppence broke in impatiently:

"But why has it all cropped up again? The war's over."

A hint of alertness came into Mr. Carter's manner.

"Because it seems that the papers were not destroyed after all, and that they might be resurrected to-day with a new and deadly significance."

Tuppence stared. Mr. Carter nodded.

"Yes, five years ago, that draft treaty was a weapon in our hands; to-day it is a weapon against us. It was a gigantic blunder. If its terms were made public, it would mean disaster.... It might possibly bring about another war—not with Germany this time! That is an extreme possibility, and I do not believe in its likelihood myself, but that document undoubtedly implicates a number of our statesmen whom we cannot afford to have discredited in any way at the present moment. As a party cry for Labour it would be irresistible, and a Labour Government at this juncture would, in my opinion, be a grave disability for British trade, but that is a mere nothing to the REAL danger."

He paused, and then said quietly:

"You may perhaps have heard or read that there is Bolshevist influence at work behind the present Labour unrest?"

Tuppence nodded.

"That is the truth. Bolshevist gold is pouring into this country for the specific purpose of procuring a Revolution. And there is a certain man, a man whose real name is unknown to us, who is working in the dark for his own ends. The Bolshevists are behind the Labour unrest—but this man is BEHIND THE BOLSHEVISTS. Who is he? We do not know. He is always spoken of by the unassuming title of 'Mr. Brown.' But one thing is certain, he is the master criminal of this age. He controls a marvellous organization. Most of the Peace propaganda during the war was originated and financed by him. His spies are everywhere."

"A naturalized German?" asked Tommy.

"On the contrary, I have every reason to believe he is an Englishman. He was pro-German, as he would have been pro-Boer. What he seeks to attain we do not know—probably supreme power for himself, of a kind unique in history. We have no clue as to his real personality. It is reported that even his own followers are ignorant of it. Where we have come across his tracks, he has always played a secondary part. Somebody else assumes the chief role. But afterwards we always find that there has been some nonentity, a servant or a clerk, who has remained in the background unnoticed, and that the elusive Mr. Brown has escaped us once more."

"Oh!" Tuppence jumped. "I wonder——"

"Yes?"

"I remember in Mr. Whittington's office. The clerk—he called him Brown. You don't think——"

Carter nodded thoughtfully.

"Very likely. A curious point is that the name is usually mentioned. An idiosyncrasy of genius. Can you describe him at all?"

"I really didn't notice. He was quite ordinary—just like anyone else."

Mr. Carter sighed in his tired manner.

"That is the invariable description of Mr. Brown! Brought a telephone message to the man Whittington, did he? Notice a telephone in the outer office?"

Tuppence thought.

"No, I don't think I did."

"Exactly. That 'message' was Mr. Brown's way of giving an order to his subordinate. He overheard the whole conversation of course. Was it after that that Whittington handed you over the money, and told you to come the following day?"

Tuppence nodded.

"Yes, undoubtedly the hand of Mr. Brown!" Mr. Carter paused. "Well, there it is, you see what you are pitting yourselves against? Possibly the finest criminal brain of the age. I don't quite like it, you know. You're such young things, both of you. I shouldn't like anything to happen to you."

"It won't," Tuppence assured him positively.

"I'll look after her, sir," said Tommy.

"And I'll look after YOU," retorted Tuppence, resenting the manly assertion.

"Well, then, look after each other," said Mr. Carter, smiling. "Now let's get back to business. There's something mysterious about this draft treaty that we haven't fathomed yet. We've been threatened with it—in plain and unmistakable terms. The Revolutionary element as good as declare that it's in their hands, and that they intend to produce it at a given moment. On the other hand, they are clearly at fault about many of its provisions. The Government consider it as mere bluff on their part, and, rightly or wrongly, have stuck to the policy of absolute denial. I'm not so sure. There have been hints, indiscreet allusions, that seem to indicate that the menace is a real one. The position is much as though they had got hold of an incriminating document, but couldn't read it because it was in cipher—but we know that the draft treaty wasn't in cipher—couldn't be in the nature of things—so that won't wash. But there's SOMETHING. Of course, Jane Finn may be dead for all we know—but I don't think so. The curious thing is that THEY'RE TRYING TO GET INFORMATION ABOUT THE GIRL FROM US."

"What?"

"Yes. One or two little things have cropped up. And your story, little lady, confirms my idea. They know we're looking for Jane Finn. Well, they'll produce a Jane Finn of their own—say at a pensionnat in Paris." Tuppence gasped, and Mr. Carter smiled. "No one knows in the least what she looks like, so that's all right. She's primed with a trumped-up tale, and her real business is to get as much information as possible out of us. See the idea?"

"Then you think"—Tuppence paused to grasp the supposition fully—"that it WAS as Jane Finn that they wanted me to go to Paris?"

Mr. Carter smiled more wearily than ever.

"I believe in coincidences, you know," he said.