Allerdyke went off to Hull, post-haste, because of a telephone call which roused him out of bed an hour before his usual time. It came from Chettle, the New Scotland Yard man who had been sent down to Hull as soon as the news of Lydenberg's murder arrived. Chettle asked Allerdyke to join him by the very next express, and to come alone; he asked him, moreover, not to tell Mr. Franklin Fullaway whither he was bound. And Allerdyke, having taken a quick glance at a time-table, summoned Gaffney, told him of his journey, bade him keep his tongue quiet at the Waldorf, wrote his hasty note to Appleyard, dressed, and hurried away to King's Cross. He breakfasted on the train, and was in Hull by one o'clock, and Chettle hailed him as he set foot on the platform, and immediately led him off to a cab which awaited them outside the station.

"Much obliged to you for coming so promptly, Mr. Allerdyke," said the detective. "And for coming by yourself—that was just what I wanted."

"Aye, and why?" asked Allerdyke. "Why by myself? I've been wondering about that all the way down."

Chettle, a sleek, comfortable-looking man, with a quiet manner and a sly glance, laughed knowingly, twiddling his fat thumbs as he leaned back in the cab. "Oh, well, it doesn't do—in my opinion—to spread information amongst too many people, Mr. Allerdyke," he said. "That's my notion of things, anyway. I just wanted to go into a few matters with you, alone, d'ye see? I didn't want that American gentleman along with you. Eh?"

"Now, why?" asked Allerdyke. "Out with it!"

"Well, you see, Mr. Allerdyke," answered the detective, "we know you. You're a man of substance, you've got a big stake in the country—you're Allerdyke, of Allerdyke and Partners, Limited, Bradford and London. But we don't know Fullaway. He may be all right, but you could only call him a bird of passage, like. He can close down his business and be away out of England to-morrow, and, personally, I don't believe in letting him into every secret about all this affair until we know more about him. You see, Mr. Allerdyke, there's one thing very certain—so far as we've ascertained at present, nobody but Fullaway, and possibly whoever's in his employ, was acquainted with the fact that your cousin was carrying those jewels from Russia to England. Nobody in this country, at any rate. And—it's a thing of serious importance, sir."

Just what Appleyard had said!—what, indeed, no one of discernment could help saying, thought Allerdyke. The sole knowledge, of course, was with Fullaway and his lady clerk—so far as was known. Therefore—

"Just so," he said aloud. "I see your point—of course, I've already seen it. Well, what are we going to do—now? You've brought me down here for something special, no doubt."

"Quite so, sir," answered Chettle composedly. "I want to draw your attention to some very special features and to ask you certain questions arising out of 'em. We'll take things in order, Mr. Allerdyke. We're driving now to the High Street—I want to show you the exact spot where Lydenberg was shot dead. After that we'll go to the police-station and I'll show you two or three little matters, and we'll have a talk about them. And now, before we get to the High Street, I may as well tell you that on examining Lydenberg's body very little was found in the way of papers—scarcely anything, and nothing connecting him with your cousin's affair—in fact, the police here say they never saw a foreign gentleman with less on him in that way. But in the inside pocket of his overcoat there was a postcard, which had been posted here in Hull. Here it is—and you'll see that it was the cause of taking him to the spot where he was shot."

Chettle took from an old letter-case an innocent-looking postcard, on one corner of which was a stain.

"His blood," he remarked laconically. "He was shot clean through the heart. Well, you see, it's a mere line."

Allerdyke took the card and looked at it with a mingled feeling of repulsion and fascination. The writing on it was thin, angular, upright, and it suggested foreign origin. And the communication was brief—and unsigned—

"High Street morning eleven sharp left-hand side old houses."

"You don't recognize that handwriting, of course, Mr. Allerdyke?" asked
Chettle. "Never seen it before, I suppose?"

"No!" replied Allerdyke. "Never. But I should say it's a foreigner's."

"Very likely," assented Chettle. "Aye, well, sir, it lured the man to his death. And now I'll show you where he died, and how easy it was for the murderer to kill him and get away unobserved."

He pulled the cab up at the corner of the High Street, and turned southward towards the river, looking round at his companion with one of his sly smiles.

"I daresay that you, being a Yorkshireman, Mr. Allerdyke, know all about this old street," he remarked as they walked forward. "I never saw it, never heard of it, until the other day, when I was sent down on this Lydenberg business, but it struck me at once. I should think it's one of the oldest streets left in England."

"It is," answered Allerdyke. "I know it well enough, and I've seen it changed. It used to be the street of the old Hull merchants—they had their houses and warehouses all combined, with gardens at the back running down to the river Hull. Queer old places there used to be in this street, I can tell you when I was a lad!—of late years they've pulled a lot of property down that had got what you might call thoroughly worm-eaten—oh, yes, the place isn't half as ancient or picturesque as it was even twenty years ago!"

"There's plenty of the ancient about it still, for all that," observed Chettle, with a dry laugh. "There was more than enough of it for Lydenberg the other day, at any rate. Now, then, you remember what it said on the postcard—he was to walk down the High Street, on the left-hand side, at eleven o'clock? Very well—down the High Street he walks, on this side which we are now—he strolls along, by these old houses, looking about him, of course, for the person he was to meet. The few people who were about down here that morning, and who saw him, said that he was looking about from side to side. And all of a sudden a shot rang out, and Lydenberg fell—just here—right on this very pavement."

He pulled Allerdyke up in a narrow part of the old street, jointed to the flags, and then to the house behind them—an ancient, ramshackle place, the doors and windows of which were boarded up, the entire fabric of which showed unmistakable readiness for the pick and shovel of the house-breaker. And he laid a hand on one of the shattered windows, close by a big hole in the decaying wood.

"There's no doubt the murderer was hidden behind this shutter, and that he fired at Lydenberg from it, through this hole," he said. "So, you see, he'd only be a few feet from his man. He was evidently a good shot, and a fellow of resolute nerve, for he made no mistake. He only fired once, but he shot Lydenberg clean through the heart, dead!"

"Anybody see it happen?" asked Allerdyke, staring about him at the scene of the tragedy, and thinking how very ordinary and commonplace everything looked. "I suppose there'd be people about, though the street, at this end, anyway, isn't as busy as it once was?"

"Several people saw him fall," answered Chettle.

"They say he jumped, spun round, and fell across the pavement. And they all thought it was a case of suicide. That, of course, gave the murderer a bigger and better chance of making off. You see, as these people saw no assailant, it never struck 'em that the shot had been fired from behind this window. When they collected their thoughts, found it wasn't suicide, and realized that it was murder, the murderer was—Lord knows where! From behind these old houses, Mr. Allerdyke, there's a perfect rabbit-warren of alleys, courts, slums, twists, and turns! The man could slip out at the back, go left or right, mix himself up with the crowd on the quays and wharves, walk into the streets, go anywhere—all in a minute or two."

"Clever—very clever! You've no clue?" asked Allerdyke.

"None; not a scrap!" replied the detective. "Bless you, there's score of foreigners knocking about Hull. Scores! Hundreds! We've done all we can, the local police and myself—we've no clue whatever. But, of course, it was done by one of the gang."

"By one of the gang!" exclaimed Allerdyke. "Ah you've got a theory of your own, then?"

Chettle laughed quietly as they turned and retraced their steps up the street.

"It 'ud be queer if I hadn't, by this time," he answered. "Oh yes, I've thought things out pretty well, and I should say our people at the Yard have come to the same conclusion that I have—I'm not conceited enough, Mr. Allerdyke, to fancy that I'm the only person who's arrived at a reasonable theory, not I?"

"Well—what is your theory?" asked Allerdyke.

"This," replied the detective. "The whole thing, the theft of the Princess Nastirsevitch's jewels from your cousin, of Miss de Longarde's or Lennard's jewels, was the work of a peculiarly clever gang—though it may be of an individual—who made use of both Lydenberg and the French maid as instruments, and subsequently murdered those two in order to silence them forever. I say it may be the work of an individual—it's quite possible that the man who killed the Frenchwoman is also the man who shot Lydenberg—but it may be the work of one, two, or three separate persons, acting in collusion. I believe that Lydenberg was the actual thief of the Princess's jewels from your cousin; that the Frenchwoman actually stole her mistress's jewels. But as to how it was worked—as to who invented and carried out the whole thing—ah!"

"And to that—to the real secret of the whole matter—we haven't the ghost of a clue!" muttered Allerdyke. "That's about it, eh?"

Chettle laughed—a sly, suggestive laugh. He gave his companion one of his half-apologetic looks.

"I'm not so sure, Mr. Allerdyke," he said. "We may have—and that's why I wanted to see you by yourself. Come round to the police-station."

In a quiet room in the usual drab and dismal atmosphere which Allerdyke was beginning to associate with police affairs, Chettle produced the personal property of the dead man, all removed, he said, from the Station Hotel, for safe keeping.

"There's little to go on, Mr. Allerdyke," he said, pointing to one article after another. "You'll remember that the man represented himself as being a Norwegian doctor, who had come to Hull on private business. He may have been that—we're making inquiries about him in Christiania, where he hailed from. According to those who're in a position to speak, his clothing, linen, boots, and so on are all of the sort you'd get in that country. But he'd no papers on him to show his business, no private letters, no documents connecting him with Hull in any way: he hadn't even a visiting-card. He'd a return ticket—from Hull to Christiania—and he'd plenty of money, English and foreign. When I got down here, I helped the local police to go through everything—we even searched the linings of his clothing and ripped his one handbag to pieces. But we've found no more than I've said. However—I've found something. Nobody knows that I've found it. I haven't told the people here—I haven't even reported it to headquarters in London. I wanted you to see it before I spoke of it to a soul. Look here!"

Chettle opened a square cardboard box in which certain personal effects belonging to Lydenberg had been placed—one or two rings, a pocket-knife, his purse and its contents, a cigar-case, his watch and chain. He took up the watch, detached it from the chain, and held it towards Allerdyke, who was regarding these proceedings with intense curiosity.

"You see this watch, Mr. Allerdyke," he said. "It's a watch of foreign make—Swiss—and it's an old one, a good many years old, I should say. Consequently, it's a bit what we might call massive. Now, I was looking at it yesterday—late last night, in fact—and an idea suddenly struck me. In consequence of that idea, I opened the back of the watch, and discovered—that!"

He snapped open the case of the watch as he spoke and showed Allerdyke, neatly cut out to a circle, neatly fitted into the case, a photograph—the photograph of James Allerdyke! And Allerdyke started as if he had been shot, and let out a sharp exclamation.

"My God!" he cried. "James! James, by all that's holy—and in there!"

"You recognize it, of course?" said Chettle, with a grim smile. "No doubt of it, eh?"

"Doubt! Recognize!" exclaimed Allerdyke. "Lord, man—why, I took it myself, not two months ago!"