Once outside the Pompadour Hotel the chief and his subordinate hurried at a great pace towards the Lancaster Gate entrance to Kensington Gardens. And when they had crossed Bayswater Road the superior pulled himself up, took a breath, and looked around him.

"No sign of them yet, Chettle," he observed. "Did he say at once?"

"Said they'd be on their way in two minutes, sir," answered Chettle. "And it wouldn't take them many minutes to run up here."

"I wonder what it's all about?" mused the chief. "Some new development since we left the Yard, of course. Well—I think we may probably find something in this parcel, Chettle, that will surprise us as much as any new development can possibly do. It strikes me—"

"Here they are, sir!" interrupted Chettle. He had lingered on the kerb, looking towards the rise of the road going towards the Marble Arch, and his quick eyes had spotted a closed taxi-cab which came out of the Marlborough Gate at full speed and turned down in their direction. "Blindway and two others," he announced. "Seems to be in force, sir, anyhow!"

The taxi-cab pulled up at the little gate leading into Kensington Gardens by the pumping-station, and Blindway, followed by two other men, hurriedly descended and joined his superior.

"Well, what is it?" demanded the chief. "Something new? And about this affair?"

Blindway made a gesture suggesting that they should enter the Gardens; once within he drew the chief aside, leaving his companions with Chettle.

"About half an hour ago," he said, "a telephone message came on from the City police. They said they'd received some queerish information about this affair, but only particularly about the death of that man down at the hotel in the Docks. Their information ran to this—that the actual murderer has an appointment with some of his associates this afternoon at that tea-house in Hyde Park, and that if the City police would send some plain-clothes men up there he'll be pointed out. So the City lot want us to join them, and I was sent along to meet you here, sir—I've brought those two men and of course there's Chettle. We're all to go along to this tea-house, not in a body, naturally, but to sort of drop in, and to wait events. Of course, sir, that last murder occurred in the City, and so the City police want to come in at it, and—"

"No further details?" asked the chief, obviously puzzled. "Nothing as to who's going to point out the murderer, and so on?"

"Nothing!" replied Blindway. "At least, nothing reported to us. All we've got to do is to be there, on the spot, and to keep our eyes open for the critical moment."

"And what time is the critical moment to be?" asked the chief, a little superciliously. "It all seems remarkably vague, Blindway—why couldn't they give us more news?"

"Don't know, sir—they seemed purposely vague," replied the detective. "However, the time fixed is two o'clock. To be there about two—that was the request—at least four of us."

The chief turned and summoned the other three men.

"You'd better break up," he said. "Two of you approach the place from one way—two from another. It's now a quarter-past one—you've plenty of time. Stroll across the park to this spot—I'll join you by two o'clock. I believe you can get light refreshments at this tea-house; get yourselves something, so as to look like mere loungers—but keep your eyes open."

"Do you want me, sir?" asked Chettle, eyeing the parcel with evident desire to know what mystery it concealed.

"No—you go with Blindway," answered the chief. "He'll tell you what's happened. I must join Mr. Allerdyke and Mr. Appleyard—then we'll come over to you. Don't take any notice of us."

The four detectives went off into Hyde Park, and there separated in couples; the chief turned and went along the straight path which runs parallel with Bayswater Road just within the shrubberies of Kensington Gardens. Presently he caught sight of Allerdyke and Appleyard, who occupied two chairs under a shady hawthorn tree, and he laid hold of another, dragged it to them, and sat down. Each looked a silent inquiry, and the chief, with a smile, held up the parcel.

"Chettle and I," he said, "have, in the presence of the manager and manageress of the Pompadour, made a thorough examination of the room and the belongings of the young lady who resides there under the name of Miss Slade. There is not a jot or tittle of anything there to show that she is also Mrs. Marlow—except one thing. That, Mr. Allerdyke, is the all-important photograph of your cousin James, which is hanging, in a neat silver frame, over her mantelpiece. What do you think of that, gentlemen?"

"Odd!" said Appleyard, after a moment's reflective silence.

"Very queer!" said Allerdyke frowning. "Very queer, indeed—considering."

"Queer and odd!" assented the chief. "As to considering—well, I don't quite know what it is that we are considering. If Miss Slade, alias Mrs. Marlow, is a member of the gang—if there is one—which killed and robbed James Allerdyke, it's a decidedly odd and queer thing that she should frame the victim's portrait and hang it where she'll see it last thing at night and first thing in the morning. Most extraordinary! And it's made me think a good deal. I believe you once said, Mr. Allerdyke, that your cousin was a bit of a ladies' man?"

"Bit that way inclined, was James," replied Allerdyke laconically. "Yes—he fancied the ladies a bit, no doubt. In quite a proper way, you know—liked their society, and so on."

"Just so!" assented the chief. "Well, I wonder if he and Miss Slade, alias Mrs. Marlow, knew each other at all—outside business? But it's not much use to speculate on that just now—we've more urgent matters to attend to. And first—this!"

He had put a copy of a morning newspaper round the small brown paper parcel, and now took it off and showed the parcel itself to the two wondering men. One of them at any rate uttered a sharp exclamation.

"Brown paper, sealed with black wax!" said Allerdyke, remembering what Chettle had told him. "Good Lord—what—"

"I don't suppose this is the original brown paper, nor these the original dabs of black wax," remarked the chief as he produced a pocket pen-knife. "But this parcel, gentlemen, was recently confided by Miss Slade to the care of the manageress of the Pompadour, to be put in the hotel safe—from which it was produced to me twenty minutes ago. And—I am now going to see what it contains."

The others sat in absorbed silence while the chief delicately removed the wrappings of the mysterious parcel. A sheet of brown paper, a sheet of cartridge paper beneath it—and within these very ordinary envelopings an old cigar-box, loosely tied about with a bit of knotted string.

"Now for it!" said the chief. "The box contains—"

He raised the lid as the other two leaned nearer. A stray ray of sunlight, filtering through the swaying boughs of the hawthorn, shot down on the box as the chief lifted a wad of soft paper and revealed a glittering mass of pearls and diamonds.

"The Princess Nastirsevitch's jewels!" said the chief softly. "That's just what I expected ever since the manageress gave me this parcel. This, of course, is the parcel which your cousin sent that night from Hull, Mr. Allerdyke. It fell into Mrs. Marlow's hands—alias Miss Slade—and here it is! That's all right."

The other two men stared at the contents of the cigar-box, then at the chief, then at each other. A deep silence had fallen—it was some minutes before Allerdyke broke it.

"All wrong, I should say!" he muttered. "However, if those are the things—I only say if, mind—I suppose we're a step nearer to something else. But—what?"

The chief, who appeared to both of them to be strangely phlegmatic about the whole affair, proceeded to close the box, re-invest it in its wrappings, and tie it about with the original string.

"We are certainly a step nearer to a good deal," he said, making a neat job of his parcel and patting it affectionately as if he had been a milliner's apprentice doing up a choice confection. "And the next thing we do is to take a walk together into Hyde Park. On the way I will tell you why we are going there—that is, I will tell you what I know of the reason for such an expedition. It isn't much—but it has certain possibilities."

The two North-countrymen listened with great curiosity as they marched across the grass towards the tea-house. Each possessed the North-country love of the mysterious and the bizarre—this last development tickled their fancy and stirred their imagination.

"What on earth d'ye make out of it all?" asked Allerdyke. "Gad!—it's more like a children's game of hide-and-seek in an old house of nooks and corners than what I should have imagined police proceedings would be. What say you, Ambler?"

"I don't know how much romance and adventure there usually are in police proceedings," replied Appleyard cautiously.

"A good answer, Mr. Appleyard," said the chief laughing. "Ah, there's a lot more of both than civilians would think, in addition to all the sordid and dismal details. What do I make out of it, Mr. Appleyard? Why—I think somebody has all this time been making a special investigation of this mystery for himself, and that at last he's going to wind it up with a sensational revelation to—us! Don't you be surprised if you've an application for that fifty thousand pound reward before to-night!"

"You really think that?" exclaimed Allerdyke incredulously.

"I shouldn't be surprised," answered the chief, "Something considerable is certainly at hand. Now let us settle our plan of campaign. This tea-garden, I remember, is a biggish place. We will sit down at one of the tables—we will appear to be three quiet gentlemen disposed to take a cup of coffee with our cigars or cigarettes—we will be absorbed in our own conversation and company, but at the same time we will look about us. Therefore, use your eyes, gentlemen, as much as you like—but don't appear to take any particular interest in anything you see, and don't openly recognize any person you set eyes on."

It was a very warm and summer-like day, and the lawns around the tea-house were filled with people, young and old. Some were drinking tea, some coffee; some were indulging in iced drinks. Nursemaids and children were much in evidence under the surrounding trees; waitresses were flitting about hither and thither: there was nothing to suggest that this eminently London park scene was likely to prove the setting of the last act of a drama.

"You're much more likely to see and to recognize than we are," remarked Allerdyke, as the three gathered round a table on the edge of the crowd. "For my part I see nothing but men, women, and children—except that I also see Chettle, sitting across yonder with another man who's no doubt one of your lot."

"Just so," assented the chief. He gave an order for coffee to a passing waitress, lighted a cigar which Allerdyke offered him, and glanced round as if he were looking at nothing in particular. "Just so. Well, I see my own four men—I also see at least six detectives who belong to the City police, and there may be more. But I know those six personally. They are spread about, all over the place, and I daresay that every man is very much on the stretch, innocent enough as he looks."

"Six!" exclaimed Appleyard. "And four of yours! That looks as if they expected to have to tackle a small army!"

"You never know what you may have to tackle in affairs like this," replied the chief. "Nothing like having reserves in hand, you know. Now let me give you a tip. It is almost exactly two o'clock. Never mind the people who are already here, gentlemen. Keep your eyes open on any new-comers. Look out—quietly—for folk who seem to drop in as casually as we do. Look, for example, at those two well-dressed men who are coming across the sward there, swinging their sticks. They—"

Allerdyke suddenly bent his head towards the table.

"Careful!" he said. "Gad!—I know one of 'em, anyhow. Van Koon, as I live!"

CHAPTER XXXII
THE CHILVERTON ANTI-CLIMAX

The chief allowed himself to take a quick searching glance at the two men he had indicated. He had already heard of Van Koon and of his sudden disappearance from the hotel after the chance encounter with Chilverton, and he now regarded him with professional interest.

"The tall man, you mean?" he asked.

"Just so," answered Allerdyke. "The other man I don't know. But that's Van Koon. What's he here for, now? Is he in this, after all?"

The chief made no reply. He was furtively watching the two men, who had dropped into chairs at a vacant table beneath the shade of the trees and were talking to a waitress. Having taken a good look at Van Koon, he turned his attention to Van Koon's companion, a little, dapper man, smartly dressed in bright blue serge, and finished off with great care in all his appointments. He seemed to be approaching middle age; there were faint traces of grey in his pointed beard and upward-twisted moustaches; he carried his years, however, in very jaunty fashion, and his white Homburg hat, ornamented with a blue ribbon, was set at a rakish angle on the side of his close-cropped head. In his right eye he wore a gold-rimmed monocle; just then he was bringing it to bear an the waitress who stood between himself and his companion.

"You don't know the other man, either of you?" asked the chief suddenly.

Allerdyke shook his head, but Appleyard nodded.

"I know that chap by sight," he said. "I've seen him in the City—about Threadneedle Street—two or three times of late. He's always very smartly dressed—I took him for a foreigner of some sort."

The chief turned to his coffee.

"Well—never mind him," he said. "Pay no attention—so long as that man is Van Koon, I'll watch him quietly. But you may be sure he has come here on the same business that has brought us here. I—"

Allerdyke, whose sharp eyes were perpetually moving round the crowded enclosure and the little groups which mingled outside it, suddenly nudged the chief's elbow.

"Miss Slade!" he whispered. "And—Rayner!"

Appleyard had caught sight of his two fellow inmates of the Pompadour at the very moment in which Allerdyke espied them. He slightly turned away and bent his head; Allerdyke followed his example.

"You can't mistake them," he said to the chief. "I've described the man to you—a hunchback. They're crossing through the crowd towards the tea-house door."

"And they've gone in there," replied the chief in another minute. "Um!—this is getting more mysterious than ever. I wish I could get a word with some of our men who really know something! It seems to me—"

But at that moment Blindway came strolling along, his nose in the air, his eyes fixed on the roofs of the houses outside the park, and he quietly dropped a twisted scrap of paper at his superior's feet as he passed. The chief picked it up, spread it out on the marble-topped table, and read its message aloud to his companions.

"City men say the informant is here and will indicate the men to be arrested in a few minutes."

The chief tore the scrap of paper into minute shreds and dropped them on the grass.

"Things are almost at the crisis," he murmured with a smile. "It seems that we, gentlemen, are to play the part of spectators. The next thing to turn up—"

"Is Fullaway!" suddenly exclaimed Allerdyke, thrown off his guard and speaking aloud. "And, by Gad!—he's got that man Chilverton with him. This—by the Lord Harry, he's caught sight of us, too!"

Fullaway was coming quickly up the lawn from the direction of the Serpentine; he looked unusually alert, vigorous, and bustling; by his side, hurrying to keep pace with him, was the New York detective. And Fullaway's keen eyes, roving about, fell on Allerdyke and the chief and he made through the crowd in their direction, beckoning Chilverton to follow.

"Hullo—hullo!" he exclaimed, clapping a hand on Allerdyke's shoulder, nodding to the chief, and staring inquisitively at Appleyard. "So you're here, too, eh, Allerdyke? It wasn't you who sent me that mysterious message, was it?"

"What message?" growled Allerdyke. "Be careful! Don't attract attention—there are things going on here, I promise you! Drop into that chair, man—tell Chilverton to sit down. What message are you talking about?"

Fullaway, quick to grasp the situation, sat down in a chair which Appleyard pulled forward and motioned his companion to follow his example.

"I got a queer message—typewritten—on a sheet of notepaper which bore no address, about an hour ago," he said. "It told me that if I came here, to this Hyde Park tea-house, at two o'clock, I'd have this confounded mystery explained. No signature—nothing to show who or where it came from. So I set out. And just as I was stepping into a taxi to come on here, I met Chilverton, so he came along with me. What brings you, then? Similar message, eh? And what—"

"Hush!" whispered Appleyard. "Miss Slade's coming out of the tea-house!

And who's the man that's with her?"

All five men glanced covertly over their shoulders at the open door of the tea-house, some twenty to thirty yards away. Down its steps came Miss Slade, accompanied by a man whom none of them had ever seen before—a well-built, light-complexioned, fair-haired man, certainly not an Englishman, but very evidently of Teutonic extraction, who was talking volubly to his companion and making free use of his hands to point or illustrate his conversation. And when he saw this man, the chief turned quickly to Allerdyke and intercepted a look which Allerdyke was about to give him—the same thought occurred to both. Here was the man described by the hotel-keeper of Eastbourne Terrace and the shabby establishment away in the Docks!

"Miss Slade!" exclaimed Fullaway. "What on earth are you talking about?

That's my secretary, Mrs. Mar—"

"Sh!" interrupted the chief. "That's one of your surprises, Mr. Fullaway!

Quiet, now, quiet. Our job is to watch. Something'll happen in a minute."

Miss Slade and her talkative companion edged their way through the crowd and passed out to an open patch of grass whereon a few children were playing. And as they went, two or three men also separated themselves from the idlers around the tables and strolled quietly and casually in the same direction. Also, Van Koon and the man with him left their table, and, as if they had no object in life but mere aimless chatter and saunter, wandered away towards the couple who had first emerged from the enclosure. And thereupon, Fullaway, not to be repressed, burst out with another exclamation.

"My God, Chilverton!" he cried. "There is Van Koon! And, by all that's wonderful, Merrifield with him. Now what—"

The New York detective, who was under no orders, and knew no reason why he should restrain himself, wasted no time in words. Like a flash, he had leapt from his chair, threaded his way through the surrounding people, and was after his quarry. And with a muttered exclamation of anger, the chief rose and followed—and it seemed to Allerdyke that almost at the same instant a score of men, up to that moment innocently idling and lounging, rose in company.

"Damn it!" he growled, as he and Appleyard got up. "That chap's going to spoil everything. What is he after? Confound you, Fullaway!—why couldn't you keep quiet for a minute? Look there!"

Van Koon had turned and seen Chilverton. So, too, had Van Koon's companion. So, also, had Miss Slade and the man she was walking with. That man, too, saw the apparent idlers closing in upon him. For a second he, and Van Koon, and the other man stared at each other across the grass; then, as with a common instinct, each turned to flee—and at that instant Miss Slade, with a truly feminine cry, threw herself upon her companion and got an undeniably firm grip on his struggling arms.

"This is the Eastbourne Terrace man!" she panted as Allerdyke and half-a-dozen detectives relieved her. "Get the other two—Van Koon and Merrifield. Quick!"

But Van Koon was already in the secure grip of Chilverton, and the person in the light blue suit was being safely rounded up by a posse of grim-faced men.