Compelled against my will to accompany the inspector to the police head-quarters in the High Street, I made a statement ­a rather lame one, I fear.

I concealed the fact that the lady of the previous night’s conference was my wife, and explained my visit to Stamford, and my inquiries at the George, by the fact that I had met the man Lewis abroad, and had had some financial dealings with him, which, I now suspected, were not altogether square.  So, hearing that he had motored to the north, I had followed, and had inquired at several of the well-known motoring hotels for news of him, being unsuccessful until I had arrived at Stamford.

This story would, of course, not have held water had Miss Hammond, the manageress, been present.  Happily, however, she had not accompanied me, hence I was able to concoct a somewhat plausible excuse to the local superintendent.

“Then you actually know nothing concerning these people?” he asked, regarding me shrewdly.

“Nothing beyond the fact of meeting Lewis abroad, and very foolishly trusting in his honesty.”

The superintendent smiled.  I think he regarded me as a bit of a fool.  Probably I had been.

“They are a clever gang, no doubt,” he declared.  “The Archduchess’s necklace must have been stolen by some one travelling in the train.  I’ve been on to Scotland Yard by telephone, and there seems a suspicion because at Grantham ­the last stopping-place before London ­a ticket-collector boarded the train.  He was a stranger to the others, but they believed that he had been transferred from one or other of the branches to the main line, and being in the company’s uniform they, of course, accepted him.  He collected the tickets en route, as is sometimes done, and at Finsbury Park descended, and was lost sight of.  Here again the busy collectors came and demanded tickets, much to the surprise of the passengers, and the curious incident was much commented upon.”

“Then the bogus collector was the thief, I suppose?”

“No doubt.  He somehow secured the dressing-bag and dropped it out at a point between Grantham and Essendine ­a spot where he knew his accomplices would be waiting ­a very neatly-planned robbery.”

“And by persons who are evidently experts,” I said.

“Of course,” replied the grey-haired superintendent.  “The manner in which the diamonds have been quickly transferred from hand to hand and carried out of the country is sufficient evidence of that.  The gang have now scattered, and, for aught we know, have all crossed the Channel by this time.”

“Well,” I assured him; “I know nothing more of the affair than what I have told you.  If I were an accomplice I should hardly be here ­making inquiries concerning them.”

“I don’t know so much about that,” he replied, rather incredulously.  “Such an action has been known before, in order to place the police upon a wrong scent.  I fear I must ask you to remain here, in Stamford, until this evening, while I make some inquiry into your bona fides, sir.”

“What!” I cried.  “You intend to detain me!”

“There is no indignity,” he declared.  “You may go about the town where you will ­providing you do not attempt to leave it.  I regret, but it is my duty to ascertain who and what you are, Mr. Biddulph.”

I had given him my card, and he, seeing the look of annoyance upon my face, added ­

“I can only express apologies, sir.  But you will see it is my duty.  You have admitted knowledge of at least one of the mysterious gang.”

“Very well,” I replied reluctantly; “make what inquiries you will.”  And I gave him the address of my solicitors and my bankers.

Then, walking out of the office, I strolled down the quiet old High Street into the market place, full of evil forebodings.

Who was this man Lewis ­or Louis ­with whom my wife had escaped?

He was a blackguardly adventurer, anyhow.  He had addressed her as “dear,” and had been solicitous of her welfare throughout!  To him she had signalled from her box in the theatre, well knowing that he was making secret preparations for her elopement.  Indeed, she had written that note and placed it upon my blotting-pad before we had gone forth together, she well knowing that she would never again re-cross my threshold.

Ah!  The poignant bitterness of it all had gripped my heart.  My cup of unhappiness was now assuredly full.

How brief had been my joy; how quickly my worst fears had been realized.

About the quiet, old-world decaying town I wandered, hardly knowing whither I went.  When, every now and then, in the fading light, I found myself going into the country I turned back, mindful of my promise not to leave the place without permission.

About six I returned to the George and sat beside the fire in the lounge ­in that selfsame chair where my fugitive wife had sat.  I was eager to renew the chase, yet until I received word from the police I was compelled to remain helpless.

Old Cross, the boots, became inquisitive, but I evaded his questions, and ate my dinner alone in the small cosy coffee-room, awaiting the reappearance of Inspector Deane.  I had given my chauffeur liberty till eight o’clock, but I was all anxiety to drive back to London.

Still, if I returned, what could I do?  Sylvia and her companions had driven away ­whither was a mystery.

The Criminal Investigation Department had already issued an official description of the persons wanted, for while I had been at the police-office the inspector had been closely questioning the man Cross and Miss Hammond.

Already the police drag-net was out, and the combined police forces of Europe would, in an hour or two, be on the watch for Sylvia and her mysterious companions.

So far as the United Kingdom was concerned sixty thousand officers, detectives and constables would be furnished with a complete description of those who had held that secret consultation.  The tightest of tight cordons would be drawn.  Every passenger who embarked at English ports for abroad would be carefully scrutinized by plain-clothes men.  Every hotel-keeper, not only in London, but in the remote villages and hamlets would be closely questioned as to the identity and recent movements of his guests.  Full descriptions of Sylvia and her friends would be cabled to America, and the American police would be asked to keep a sharp look-out on passengers arriving on all boats from Europe.  Descriptions would also be sent to the police head-quarters in every European capital.

In face of that, what more could I do?

The situation had become unbearable.  Sylvia’s unaccountable action had plunged me into a veritable sea of despair.  The future seemed blank and hopeless.

Just before eight o’clock I strolled back to the police-office and reported myself, as it were.  The superintendent expressed himself perfectly satisfied with the replies he had received from London, and, with apologies, gave me leave to depart.

“Inquiry is being made along the roads in every direction from here,” he said.  “We hear that the three men and the woman called at the Bell, at Barnby Moor, and had some breakfast.  Afterwards they continued northward.”

“Barnby Moor!” I echoed.  “Why, that’s near Doncaster.”

“Yes, sir.  Motorists patronize the place a good deal.”

“And is that all that is known?” I inquired eagerly.

“All at present,” he said.  Therefore I left and, returning to the garage, mounted the car and, with head-lamps alight, drove out into the pitch darkness in the direction of Grantham.  We sped along the broad old coach-road for nearly three hours, until at last we pulled up before an ancient wayside inn which had been modernized and adapted to twentieth-century requirements.

The manager, in reply to my eager questions, said it was true that the Doncaster police had been there making inquiries regarding four motorists ­three gentlemen and a lady ­who had called there that morning and had had breakfast in the coffee-room.

The head-waiter who had attended them was called, and I questioned him.  I think the manager believed me to be a detective, for he was most courteous, and ready to give me all information.

“Yes, sir,” replied the tall, slim head-waiter.  “They came here in a great hurry, and seemed to have come a long distance, judging from the way the car was plastered with mud.  The lady was very cold, for they had an open car, and she wore a gentleman’s overcoat and a shawl tied around her head.  The tallest of the gentlemen drove the car.  They called him Lewis.”

“Did you hear them address the lady?” I asked eagerly.

“They called her Sonia, sir.”

“And you say she seemed very fatigued?”

“Very.  She went upstairs and changed her evening gown for a stuff dress, which was brought out of the car.  Then she came down and joined the others at breakfast.”

“They gave you no indication as to their destination, I suppose?”

“Well, sir, I think they were returning to London, for I heard one of the gentlemen say something about catching the boat-train.”

“They may have meant the Harwich boat-train from the north,” I remarked.

“Very likely, sir.  One portion of that train comes through Doncaster in the afternoon to Peterborough and March, while the other comes down to Rugby on the North-Western, and then goes across to Peterborough by way of Market Harborough.”

“Then they may have joined that, and if so they would just about be leaving Parkeston Quay by now!”

“If so, the police are certain to spot them,” laughed the waiter.  “They’re wanted for the theft of a princess’s jewels, they say.”

What should I do?  It was now long past ten o’clock, and I could not possibly arrive at Parkeston before early morning.  Besides, if they had really gone there, they would, no doubt, be arrested.  The man with the pimply face whose description so closely tallied with that of Reckitt, was surely too clever a criminal to run his neck into a noose by going to any port of embarkation.  Therefore I concluded that whatever had been said at table had been said with the distinct object of misleading the waiter.  The very manner in which the diamonds had been stolen showed a cunning and a daring unsurpassed.  Such men were certainly not easily trapped.

My sole thought was of Sylvia.  I could not bring myself to believe that she had wilfully forsaken her home and her husband.  Upon her, I felt confident, some species of blackmail had been levied, and she had been forced away from me by reasons beyond her control.

That incident of the photograph ­the picture believed to have been of myself ­which the foreigner tried to secure but which the man Lewis had himself destroyed, was incomprehensible.  What had been intended by the foreigner?

I gathered all the information I could in the hotel, and then, after a hasty meal, re-entered the car and set out upon the dark, cold return journey to London.

Where was Sylvia?  Who were her mysterious friends?  And, chief of all, who was that man Lewis who addressed her in such endearing terms?

What could possibly be the solution of the mystery?