Empress, all bearing the postmark of that town in the Maine-et-Loire. Others had been posted in Leipzig, Wilhelmshaven, Tours, Antwerp, Berlin-Wilmersdorf, and other places.

"The investigation is exceedingly difficult, I can assure you," he said. "I have had the assistance of some of the best scientific brains of our Empire in making comparisons and analyses. Indeed, Professor Harbge is with me from Berlin."

As he uttered those words the Professor himself, an elderly, spectacled man in grey tweeds, entered the room. I knew him and greeted him.

"We have been studying the writing-papers," the Professor said presently, as he turned over the letters, some of which were upon commercial typewriting paper, some on cheap thin paper from fashionable "blocks," and others upon various tinted paper of certain mills, as their watermarks showed. The papers were various, but the scurrilous hand was the clever and evasive one of some person who certainly knew the innermost secrets of the German Court.

"Sixteen different varieties of paper have been received at the Neues and Marmor Palaces," the Baron remarked. "Well, I have worked for two months, night and day, upon the inquiry, for, as you know, the tentacles of our Teuton octopus are everywhere. I have discovered that eleven of these varieties of paper can be purchased at a certain small stationer's shop, Lancry's, in the Boulevard Haussmann, close to the 'Printemps.' One paper especially is sold nowhere else in Paris. It is this."

And he held over a mirror a letter upon a small sheet of note-paper bearing the watermark of a bull's head.

"That paper was made at a mill in the south of Devonshire, in England, destroyed by fire five years ago. Paper of that make cannot be obtained anywhere else in France," he declared.

I at once realized how much patience must have been expended upon the inquiry, and said:

"Then you have actually fixed the shop where the writer purchased his paper?"

"Yes," he replied. "And we know that the newly-invented typewriter, a specimen one, was sold by the Maison Audibert, in Marseilles. The purchaser of the typewriter in Marseilles purchases his paper and envelopes at Lancry's, in the Boulevard Haussmann."

"Splendid!" I said enthusiastically, for it was clear that the Baron, with the thousand-and-one secret agents at his beck and call, had been able, with the Professor's aid, to fix the source of the stationery. "But," I added, "what is wanted from me?" Why, I wondered, had His Majesty sent the Baron that photograph of Elise Breitenbach?

"I want you to go with me to the central door of the 'Printemps' at four o'clock this afternoon, and we will watch Lancry's shop across the way," the Baron replied.

This we did, and from four till six o'clock we stood, amid the bustle of foot passengers, watching the small stationer's on the opposite side of the boulevard, yet without result.

Next day and the next I accompanied the prosperous cinema proprietor upon his daily vigil, but in vain, until his reluctance to tell me the reason why I had been sent to Paris annoyed me considerably.

On the fifth afternoon, just before five o'clock, while we were strolling together, smoking and chatting, the Baron's eyes being fixed upon the door of the small single-fronted shop, I saw him suddenly start, and then make pretence of utter indifference.

"Look!" he whispered beneath his breath.

I glanced across and saw a young man just about to enter the shop.

The figure was unfamiliar, but, catching sight of his face, I held my breath. I had seen that sallow, deep-eyed countenance before.