Westerham stood still gazing stupidly at the girl and holding out the jewels towards her.

When he had recovered from his great surprise he moved a step nearer to her.

“Madam,” he said, “permit me to insist that you shall take these things back.”

Without a word the girl stretched out her hand and took the jewels from him. She hid them quickly in the folds of her cloak, and all the while the expression of amaze and fear on her face did not abate.

At last she pointed to the man lying beneath the tree.

“You have not killed him?” she asked, in a low voice.

For answer, Westerham turned again and knelt at the fat man's side. He inserted his hand skilfully over the unconscious man's heart, and then rose to his feet again.

“No,” he said, almost with a laugh. “Just knocked him out; that is all. He will be all right directly, and I fancy he will be glad to walk away without assistance. I imagine he is not a character who would care for much fuss and attention at this time of the night.”

Again Westerham drew near to the girl and peered gravely and keenly, but at the same time with all deference, into her face.

“I think,” he said quietly, “that it will be better for you to walk away while we are still undisturbed. If you will allow me, I will accompany you to the gates of the park. If I may be permitted to say so, it is hardly fitting that a lady in your position, carrying so much property about with her, should be strolling around here unattended.”

His tones were so kind and so cheering, and suggested such a delicate sense of humour at the whole situation, that Lady Kathleen smiled back at him.

“At least,” she said, and now she almost laughed herself, “you are a very sturdy escort.”

Westerham said not another word except, “This is the way,” and then, guiding the girl through the trees, he reached the main path and helped Lady Kathleen to step over the low iron railing; thence he piloted her through a throng of quite incurious people to Hyde Park Corner.

She walked beside him without saying anything at all, apparently satisfied to be in his charge; and she made no demur when, on reaching the street, Westerham hailed a passing taxicab.

The man drew up at the kerb, and opening the door, Westerham assisted the girl to enter.

Then he leant forward into the darkness of the cab and said earnestly:

“I trust you will permit me to see you safely on your road. Apparently one never knows what may happen in London, and, believe me, I have no wish you should suffer a second adventure such as the one through which you have just passed.”

“Thank you,” said Lady Kathleen in a scarcely audible voice. “If you will see me as far as Trafalgar Square I shall be glad.”

Giving the order “Trafalgar Square!” Westerham entered the cab.

They drove in complete silence along Piccadilly, down St. James's Street, and through Pall-Mall, and rapidly approached the Nelson monument. As the lights of the Grand Hotel came into view, Westerham leaned towards the girl and said very gravely:

“Do you think Trafalgar Square is near enough to your home? Had I not better tell the man to put you down at the corner of Downing Street?”

The girl gave a quick gasp, and then a stifled cry.

Westerham could see her eyes shining in the dimly-lit little vehicle.

“What do you know?” she cried.

“If you mean,” answered Westerham, “what do I know of the fat man and the jewels and your mission in Hyde Park—nothing. I give you my word I know nothing at all. But I do know you are Lady Kathleen Carfax, and that your father is Prime Minister of England, and that, without any high-flown sentiments, it is at least my duty to see you reach home in safety.”

Obedient to Westerham's instructions, the cabman had pulled up at the kerb beneath the monument.

“If you are sure,” said Westerham, “that you would rather alight here, of course I must defer to your wishes. But at least permit me to follow you at a respectful distance down Whitehall. I cannot tell why, but I feel uneasy about the last stages of your journey.”

Turning towards him, the girl held out her hand impulsively.

“Thank you,” she said. “Thank you. I cannot tell you how much I thank you. You are evidently a gentleman. I ask you as a gentleman not to mention to anyone in the world what you have seen or heard to-night. Believe me,” she added with a catch in her voice, “that to-night's doings concern the honour of the best, and, as I think, the greatest, man in this country. I mean my father.”

Westerham bowed.

“You may trust me absolutely,” he said. “I give you my word of honour that not one single word of this shall pass my lips. But may I say something else? May I be allowed to make an offer of help? I have money, I have many resources at my command. I would willingly pledge myself to serve you in any way. I should be only too proud, too glad, to help.”

“No, no!” cried the girl, sharply, and with a note almost of agony in her voice.

The distress in the girl's tones was so real that Westerham made no further effort to persuade her.

He opened the door of the taxicab and assisted Lady Kathleen to step out.

Then, having paid the cabman, he turned to her side again.

“If you will allow me,” he said, “I will at least see you across the road,” and he made this suggestion with some justification, for the late after-theatre traffic was now streaming westwards.

At the top of Whitehall he turned, and lifting his hat, stood waiting for Lady Kathleen to take leave of him. Once more she stretched out her hand impulsively, and he took it in his own.

“Thank you,” she said, in the same low, earnest voice, “thank you again and again.”

“So far as I am concerned,” said Westerham, “You may rely on my absolute silence—if only,” he added with a little smile, “because there is really no one in London with whom I'm on speaking terms.”

Lady Kathleen nodded her head and searched his face with her serious eyes. Then she turned and walked quickly away.

As for Westerham, he ran quickly across to the further side of the roadway that he might watch Lady Kathleen's progress to Downing Street, for he was still fearful that she might meet with further molestation. He saw, however, that she reached the corner of the famous little cul-de-sac in safety, and, moreover, that she was saluted by an apparently surprised and startled policeman.

As Westerham walked back to Walter's Hotel he was in a most perplexed state of mind. Was it possible that he had stepped suddenly into the midst of some tragic mystery? Was it possible that it was real and actual sorrow and horror that had made the eyes of the girl in the picture—the eyes of the girl who had drawn him back to England—so wistful and so beckoning?

That a girl in Lady Kathleen Carfax's position might be suffering some profound grief, or might be the centre of some bit of distressing family history, might well be conceived. But what should take the daughter of the Prime Minister of England to Hyde Park after dark, and what extraordinary combination of inappropriate events could possibly cause her to seek the silence of such a man as he had left insensible?

Melun? It was possible that he was connected with the mystery. Westerham now remembered the man's cynical and confident smile when he had so unwisely boasted to him that he proposed to marry Lady Kathleen.

If Melun were really implicated in this business, then the methods of his villainy must be far more complicated than Westerham had anticipated. Only a very extraordinary conspiracy indeed could possibly have taken the Prime Minister's daughter into the park at such an hour.

From Westerham's own personal experience Melun was a very prince of blackmailers. Indeed, he had not troubled to deny the accusation when Westerham had made it. But even the nimble imagination of Westerham had not foreseen the possibility of blackmailing the Prime Minister, at whose back were all the forces of the law, including a discreet and silent and swiftly-acting Scotland Yard.

Westerham sat far into the night, turning all these things over in his mind; and the more he pondered over them the more convinced he became that Melun must be in some way implicated, if indeed he were not the originator of the whole business.

It was, however, upon what matter Melun could possibly blackmail Lord Penshurst that caused Westerham the most perplexity.

Obviously it was not some minor question of personal honour which involved the necessity of maintaining some sordid and disgraceful secret, or obviously Lord Penshurst's daughter would not be risking her personal safety, and to a great extent her reputation, by making such a visit to the park.

No; evidently the matter involved some great State secret, concerning which the Prime Minister had sought the confidence and assistance of his daughter. Yet Westerham could not altogether understand how this might be, because he could not conceive any matter of State which it would not be better to trust to the Secret Service than to a young girl.

Whatever it might be, the mystery embraced Lady Kathleen; and with the single-hearted desire to assist her, Westerham determined, whether it pleased her or not, that he would range himself on her side.

To do this, however, it would be necessary to discover what the mystery was, and he was still far from the solution when he fell asleep.

On the morrow he rose early, and sat till lunch-time in the reading-room holding a paper before him, but in reality setting up and then demolishing a thousand and one theories to account for Lady Kathleen's plight.

He had sent for Melun, and while he waited for him he debated with himself as to whether or not he should tax the captain with complicity in the matter. Finally he decided against such a course, seeing that an affair of such a magnitude as that in which Lady Kathleen was entangled must of a certainty outweigh in value even the great financial inducements with which he had sought to attach Melun to himself.

Finally Sir Paul resolved to cease his exploration of London and begin his exploration of the devious paths of Captain Melun, with the turnings and twistings of which he was still unacquainted.

It was quite possible that for the better conduct of his campaign against the Prime Minister Melun might require a certain amount of ready money, and in return for that ready money the captain might be led into showing Westerham sufficient of his life to enable the baronet to grasp and understand the mystery of Lady Kathleen.

When at last Captain Melun came up after lunch Westerham greeted him coldly—so coldly that the captain raised his eyebrows.

“It seems,” he said, “that you are not in a very good humour. Is London beginning to bore you?”

Sir Paul looked at him sharply. “No,” he said, thoughtfully, “not in the least, though I confess that I have to some extent exhausted its ordinary attractions. Now I propose to plunge a little deeper into its secrets and its mysteries. In this direction I am, of course, looking to you to help me.”

The captain nodded. “Quite so,” he agreed, “but I hope you realise that up to the present I have had nothing but your promises of favours to come—and times are hard.”

For answer, the baronet took out his pocket-book and counted out ten one-hundred-pound notes upon the table.

“This,” he said, “should be a sufficient guarantee of my good faith for the present. Mark you, I have had some experience of your kind before, and I do not propose to pay down a lump sum for services which you may subsequently find it inconvenient to render.

“Now I will come to the point at once. I don't propose to spend a thousand pounds for nothing—and when I say nothing, I mean for the privilege of knowing you alone. I am desirous of making the acquaintance of your friends and colleagues at once.”

Melun laughed, showing his fine teeth. “I have not the slightest objection,” he said, “and, as a matter of fact, you have chosen a particularly convenient day, for it is on Wednesdays that the heads of my business meet to discuss a few personal matters.

“To-day I will not disguise from you the fact that the discussion will be yourself. I have made known some details of your offer—but not all of them, because my friends are not so gifted with imagination as myself, and I must confess that your proposal is regarded with considerable suspicion.”

The captain moved aside and looked thoughtfully out of the window for a few moments; then he turned round on his heel sharply.

“I will be perfectly frank with you,” he said with an amazingly good attempt at breezy honesty. “All of my friends are not particularly nice people, and if they had any idea that you were likely to play them false, not even the consideration of tapping your vast wealth would restrain them from putting you out of the way.”

“There is such a thing,” said Westerham, lightly, “as killing the goose which lays the golden eggs.”

“Yes,” said the captain, gravely, “but even a supply of golden eggs may be retained at too dear a price.

“However,” he went on with an air of gaiety, “this is rather too serious a matter to consider to-day. I simply intended to throw out a kindly hint.”

“I'm sure you are very good,” said Westerham with a fine sarcasm. “I had not looked for you to be so completely considerate.”

“I am sorry,” said the captain, “to ask you to a meal which goes ill with your present position, but, truth to tell, as the evening is always a busy time with us, we find it more convenient to discuss our plans over high tea.”

He took out his watch and looked at it thoughtfully. “If we start now we shall be at Herne Hill at about five o'clock—that will suit us admirably.” “Very well,” said the baronet, picking up his hat, “I am ready to go when you are.”

At the hall door Sir Paul stopped and looked out into the street, and was in the act of hailing a passing cab when the captain stayed his hand.

“Oh, no,” he said, with a quiet laugh; “we take no cabs to Herne Hill from here. You will find it far more convenient to take a tram when there is a possibility that your movements are being followed with attention.”

Without another word he led the way down the Embankment, and on to Westminster Bridge, where the two men took a car to the Elephant and Castle.

From this point the captain took an omnibus, and twenty minutes later they were in the pretty and innocent and homely suburb of Herne Hill.

Stepping ahead with quick and unhesitating strides, Melun led the way up a long avenue, and turned into the gate of a pleasant garden, in which there stood a substantial red-brick house.

On his ringing the bell the door was opened by a German man-servant, and a moment later they were shown into a prettily-furnished drawing-room of the suburban type.

From a seat by the fire there arose an elderly lady dressed in decorous black silk. This was the hostess, Mrs. Bagley. Her face was broad and flat, and she had a pair of little black eyes that danced and glinted. Her grey hair was neatly parted beneath a black lace cap. Altogether she looked a particularly respectable middle-aged British matron. Her aspect, indeed, was so completely precise and prim, that when he turned from shaking hands with her, Sir Paul was almost taken aback at the utter contrast which the other woman in the room presented to Mrs. Bagley.

The other woman must in her time have been out of the common beautiful. She was beautiful even now, though her eyes were very tired and her face when in repose was hard and set. Her hair would have at once aroused suspicion that it was dyed, for it was lustrous and brilliant as burnished copper. But the suspicion would have been without justification, in the same way as would have been the notion that the very pronounced colour on the woman's cheeks was artificial too.

“Madame Estelle,” said Melun, by way of introduction, and his heavy-lidded eyes glanced quickly from the red-haired woman to Sir Paul. He noted with considerable satisfaction that the baronet was evidently much struck by the beauty of Estelle.

The third occupant of the room was a tall young man of the most unpleasant appearance.

He had very light blue eyes, closely set together, and a large, red, hawk-like nose. His hands were large and red, with immense knuckles and brutal, short, stubbed nails. Westerham took one of the huge red hands with a little shudder. It was cold and clammy and strong as a vice.

“If ever,” thought the baronet to himself, “I have touched the hand of a murderer, I have touched one now.”

The tall young man sat down by the window and carefully watched the baronet with his narrow, light blue eyes. The quick gaze of the elderly matron glinted and flashed all over Westerham's face. The captain looked at him sidelong. The red-haired woman alone gazed at him openly and frankly with eyes that were almost honestly blue.

There was a little pause while conversation hung fire. There was nothing for this curious collection of human beings to talk about except the baronet himself, and on this subject their tongues had to be silent as long as he remained.

Suddenly the door opened, and a portly man with a sallow, greasy face came quickly in. He stood still, with his hand on the panel of the door, and gave a short, quick gasp which caused the captain to look at him sharply.

And schooled as he was against the betrayal of any feeling, Westerham himself nearly uttered an exclamation, for the man who had entered the room so suddenly was the fat man out of whom he had knocked the sense the night before.

The fat man closed the door behind him gently, and came into the centre of the room.

“Sir Paul,” said Captain Melun, “allow me to present Mr. Bagley. Mr. Bagley is the manager of a branch of a great bank, and acts as our financier.”

Mr. Bagley's sallow and greasy countenance broke into a hideously affable smile. Westerham found himself shaking hands with the man who held Lady Kathleen's secret.

The pause which followed this introduction became so embarrassing that Mrs. Bagley suggested that they should go in to tea; and in a cheerful dining-room Westerham found himself looking curiously at the collection of tea and coffee pots, whisky decanters, bacon and eggs, and muffins and cakes, which were spread promiscuously on the clean white tablecloth.

The conversation turned on many things, but for the most part upon the weather. When the little party had eaten and drunk their fill the captain rapped sharply on the table.

There was complete silence, in which Melun rose, and having first closed the window he afterwards opened the door to satisfy himself that no one listened without.

He then returned to his seat at the table and spoke quickly and in a low voice.

“I have told you,” he said rapidly, “how I met Sir Paul.”

The baronet could not resist the luxury of a sardonic little smile.

Melun saw it and winced, but went boldly on with his subject.

“It is quite excusable,” he said, “for the richest man on the earth to desire to indulge his whims, and if we can assist Sir Paul to humour his, to his own advantage and ours, then so much the better for us all. The terms which Sir Paul has offered are generous to a degree, while the risks we run are slight. Sir Paul has not pressed us in any way. He desired in return for the money he was about to hand over to us to make the acquaintance—of my friends. He has now met them, and I trust that he is at least satisfied.”

Westerham bowed.

“For the present, therefore,” the captain continued, “there remains nothing to be said and nothing to be done. We, of course, have several things to discuss, and I am sure that Sir Paul will not take it amiss if we ask him to excuse us. It is quite impossible for him to take part in our counsels. There is no immediate hurry, but still we must talk matters over before it is much later.”

Westerham rose to his feet. Truth to tell, he desired to shake off the dust of Herne Hill, not so much to enable Captain Melun's extraordinary friends to discuss their plans, but because he was sufficiently bored to wish to leave them.

To Westerham's surprise, however, Mme. Estelle rose too.

“My carriage is, I think, waiting for me,” she said in an almost gentle voice, “and if Sir Paul will allow me I will drive him back.”

Melun gave both the red-haired woman and the baronet a distinctly ugly look. He was, indeed, about to raise some objection when Mme. Estelle spoke again.

“I will see you to-morrow,” she said, turning quickly towards him.

Melun bit his lips, but said nothing, though he followed her and the baronet out of the room and saw them to the carriage, which was a well-appointed, quiet little brougham drawn by a well-bred bay.

Westerham was somewhat puzzled by all that had taken place, but he had, at any rate, quickly divined that Mme. Estelle stood in no particular fear of Melun, and both for reasons of vanity and policy he determined to show her that he himself could, as a matter of fact, exercise some authority over the evil-looking captain.

Westerham thrust his head out of the carriage as it was driving away and said sharply to Melun, “I shall expect you to-morrow at noon.”

For quite a while they drove north in silence. It was not, indeed, until they were passing through Regent Street that Mme. Estelle turned to Westerham and spoke the first word.

“Forgive my being so blunt,” she said, “but I think you are playing an exceedingly dangerous game.”

“What it is possible for a woman to do is possible for me to do,” said Westerham.

The woman sighed. “Ah, yes, possible,” she said, “and yet with you and with me things are quite different. You have nothing to gain and everything to lose—I have nothing to lose at all.”

They drove on again in silence—a long silence, during which Westerham turned many things over in his mind, and the conclusion he came to was that it would be well to have this woman for his friend.

They were driving past the graveyard of the St. John's Wood Chapel when he turned to her almost sharply and said, “Are you sure that I have nothing to gain?”

Mme. Estelle turned and looked at him quickly, and her eyes were startled; the brilliant colour had left her face.

“What do you mean?” she cried. “You are Sir Paul, aren't you?”

“Madam,” said Westerham, almost gently, “I'm sorry if I startled you. Those who run great risks always imagine that the greatest object of every other person is to accomplish their downfall. I assure you that no such motive prompted me in making the bargain I have made with Melun.”

“Then,” said the woman, “you can have no aim unless it be mere idle curiosity?”

Westerham said nothing for the moment, but five minutes later, as though he were resuming a conversation which had been abruptly broken off, he said, “I am not so sure.”

The carriage had now passed out of the Finchley Road into a quiet cul-de-sac, and had drawn up before a high wooden door let into a garden wall.

Westerham assisted Mme. Estelle to alight. She asked him to ring the bell, which he did, and a second later the garden door opened by some unseen agency.

When she had stepped into the garden, Mme. Estelle beckoned to Westerham to follow her, and he stepped into the garden and stood beside her.

She closed the door to, glanced over her shoulder to see that she was not observed, and then caught Westerham by the coat.

“Sir Paul,” she cried in a low voice, “you are a young man. Do not destroy your life for a piece of folly. Cut yourself adrift from this while there is still time.”

Westerham took her hand and looked at her kindly. “Thank you,” he said; “thank you very much. But I am not only moved by folly to go on with this business. Some day I may explain to you. I do not know that I particularly care for going on, but there is no drawing back now.”