His various listeners had heard all that the old solicitor had said, with evident interest and attention--now, one of them voiced what all the rest was thinking.

"What makes you think that, Mr. Killick?" asked the man from New Scotland Yard. "Why should Levendale and Purvis have been trapped?"

Mr. Killick--who was obviously enjoying this return to the arena in which, as some of those present well knew, he had once played a distinguished part, as a solicitor with an extensive police-court practice--twisted round on his questioner with a sly, knowing glance.

"You're a man of experience!" he answered. "Now come!--hasn't it struck you that something went before the death of old Daniel Multenius--whether that death arose from premeditated murder, or from sudden assault? Eh?-- hasn't it?"

"What, then?" asked the detective dubiously. "For I can't say that it has --definitely. What do you conjecture did go before that?"

Mr. Killick thumped his stout stick on the floor.

"Robbery!" he exclaimed, triumphantly. "Robbery! The old man was robbed of something! Probably--and there's nothing in these cases like considering possibilities--he caught the thief in the act of robbing him, and lost his life in defending his property. Now, supposing Levendale and Purvis were interested--financially--in that property, and set their wits to work to recover it, and in their efforts got into the hands of--shall we suppose a gang?--and got trapped? Or," concluded Mr. Killick with great emphasis and meaning, "for anything we know--murdered? What about that theory?"

"Possible!" muttered Ayscough. "Quite possible!"

"Consider this," continued the old solicitor. "Levendale is a well-known man--a Member of Parliament--a familiar figure in the City, where he's director of more than one company--the sort of man whom, in ordinary circumstances, you'd be able to trace in a few hours. Now, you tell me that half-a-dozen of your best men have been trying to track Levendale for two days and nights, and can't get a trace of him! What's the inference? A well-known man can't disappear in that way unless for some very grave reason! For anything we know, Levendale--and Purvis with him--may be safely trapped within half-a-mile of Praed Street--or, as I say, they may have been quietly murdered. Of one thing I'm dead certain, anyway--if you want to get at the bottom of this affair, you've got to find those two men!"

"It would make a big difference if we had any idea of what it was that Daniel Multenius had in that packet which he fetched from his bank on the day of the murder," remarked Ayscough. "If there's been robbery, that may have been the thief's object."

"That pre-supposes that the thief knew what was in the packet," said Purdie. "Who is there that could know? We may take it that Levendale and Purvis knew--but who else would?"

"Aye!--and how are we to find that out?" asked the New Scotland Yard man. "If I only knew that much--"

But even at that moment--and not from any coincidence, but from the law of probability to which Mr. Killick had appealed--information on that very point was close at hand. A constable tapped at the door, and entering, whispered a few words to the chief official, who having whispered back, turned to the rest as the man went out of the room.

"Here's something likely!" he said. "There's a Mr. John Purvis, from Devonshire, outside. Says he's the brother of the Stephen Purvis who's name's been in the papers as having mysteriously disappeared, and wants to tell the police something. He's coming in."

The men in the room turned with undisguised interest as the door opened again, and a big, fresh-coloured countryman, well wrapped up in a stout travelling coat, stepped into the room and took a sharp glance at its occupants. He was evidently a well-to-do farmer, this, and quite at his ease--but there was a certain natural anxiety in his manner as he turned to the official, who sat at the desk in the centre of the group.

"You're aware of my business, sir?" he asked quietly.

"I understand you're the brother of the Stephen Purvis we're wanting to find in connection with this Praed Street mystery," answered the official. "You've read of that in the newspaper, no doubt, Mr. Purvis? Take a seat-- you want to tell us something? As a matter of fact, we're all discussing the affair!"

The caller took the chair which Ayscough drew forward and sat down, throwing open his heavy overcoat, and revealing a whipcord riding-suit of light fawn beneath it.

"You'll see I came here in a hurry, gentlemen," he said, with a smile. "I'd no thoughts of coming to London when I left my farm this morning, or I'd have put London clothes on! The fact is--I farm at a very out-of-the- way place between Moretonhampstead and Exeter, and I never see the daily papers except when I drive into Exeter twice a week. Now when I got in there this morning, I saw one or two London papers--last night's they were--and read about this affair. And I read enough to know that I'd best get here as quick as possible!--so I left all my business there and then, and caught the very next express to Paddington. And here I am! And now-- have you heard anything of my brother Stephen more than what's in the papers? I've seen today's, on the way up."

"Nothing!" answered the chief official. "Nothing at all! We've purposely kept the newspapers informed, and what there is in the morning's papers is the very latest. So--can you tell us anything?"

"I can tell you all I know myself," replied John Purvis, with a solemn shake of his head. "And I should say it's a good deal to do with Stephen's disappearance--in which, of course, there's some foul play! My opinion, gentlemen, is that my brother's been murdered! That's about it!"

No one made any remark--but Mr. Killick uttered a little murmur of comprehension, and nodded his head two or three times.

"Murdered, poor fellow, in my opinion," continued John Purvis. "And I'll tell you why I think so. About November 8th or 9th--I can't be sure to a day--I got a telegram from Stephen, sent off from Las Palmas, in the Canary Islands, saying he'd be at Plymouth on the 15th, and asking me to meet him there. So I went to Plymouth on the morning of the 15th. His boat, the Golconda, came in at night, and we went to an hotel together and stopped the night there. We hadn't met for some years, and of course he'd a great deal to tell--but he'd one thing in particular--he'd struck such a piece of luck as he'd never had in his life before!--and he hadn't been one of the unlucky ones, either!"

"What was this particular piece of luck?" asked Mr. Killick.

John Purvis looked round as if to make sure of general attention.

"He'd come into possession, through a fortunate bit of trading, up country in South Africa, of one of the finest diamonds ever discovered!" he answered. "I know nothing about such things, but he said it was an orange- yellow diamond that would weigh at least a hundred and twenty carats when cut, and was worth, as far as he could reckon, some eighty to ninety thousand pounds. Anyway, that was what he'd calculated he was going to get for it here in London--and what he wanted to see me about, in addition to telling me of his luck, was that he wanted to buy a real nice bit of property in Devonshire, and settle down in the old country. But--I'm afraid his luck's turned to a poor end! Gentlemen!--I'm certain my brother's been murdered for that diamond!"

The police officials, as with one consent, glanced at Mr. Killick, and by their looks seemed to invite his assistance. The old gentleman nodded and turned to the caller.

"Now, Mr. Purvis," he said, "just let me ask you a few questions. Did your brother tell you that this diamond was his own, sole property?"

"He did, sir!" answered the farmer. "He said it was all his own."

"Did he tell you where it was--what he had done with it?"

"Yes! He said that for some years he'd traded in small parcels of such things with two men here in London--Multenius and Levendale--he knew both of them. He'd sent the diamond on in advance to Multenius, by ordinary registered post, rather than run the risk of carrying it himself."

"I gather from that last remark that your brother had let some other person or persons know that he possessed this stone?" said Mr. Killick. "Did he mention that? It's of importance."

"He mentioned no names--but he did say that one or two knew of his luck, and he'd an idea that he'd been watched in Cape Town, and followed on the Golconda," replied John Purvis. "He laughed about that, and said he wasn't such a fool as to carry a thing like that on him."

"Did he say if he knew for a fact that the diamond was delivered to Multenius?" asked Mr. Killick.

"Yes, he did. He found a telegram from Multenius at Las Palmas, acknowledging the receipt. He mentioned to me that Multenius would put the diamond in his bank, till he got to London himself."

Mr. Killick glanced at the detective--the detectives nodded.

"Very good," continued Mr. Killick. "Now then--: you'd doubtless talk a good deal about this matter--did your brother tell you what was to be done with the diamond? Had he a purchaser in view?"

"Yes, he said something about that," replied John Purvis. "He said that Multenius and Levendale would make--or were making--what he called a syndicate to buy it from him. They'd have it cut--over in Amsterdam, I think it was. He reckoned he'd get quite eighty thousand from the syndicate."

"He didn't mention any other names than those of Multenius and Levendale?"

"No--none!"

"Now, one more question. Where did your brother leave you--at Plymouth?"

"First thing next morning," said John Purvis. "We travelled together as far as Exeter. He came on to Paddington--I went home to my farm. And I've never heard of him since--till I read all this in the papers."

Mr. Killick got up and began to button his overcoat. He turned to the police.

"Now you know what we wanted to know!" he said. "That diamond is at the bottom of everything! Daniel Multenius was throttled for that diamond-- Parslett's death arose out of that diamond--everything's arisen from that diamond! And, now that you police folks know all this--you know what to do. You want the man, or men, who were in Daniel Multenius's shop about five o'clock on that particular day, and who carried off that diamond. Mr. Purvis!--are you staying in town?"

The farmer shook his head--but not in the negative.

"I'm not going out of London, till I know what's become of my brother!" he said.

"Then come with me," said Mr. Killick. He said a word or two to the police, and then, beckoning Lauriston and Purdie to follow with Purvis, led the way out into the street. There he drew Purdie towards him. "Get a taxi-cab," he whispered, "and we'll all go to see that American man you've told me of--Guyler. And when we've seen him, you can take me to see Daniel Multenius's granddaughter."