"Then before you go I hope I shall be able to give you some that will be worth picking up, and keeping too," said the scientist with a faint smile; "at any rate, I think I can put you upon certain lines of enquiry which you will find it profitable to trace out." Nicol Hendry was an ambitious man, and he would have given a good deal to have known what was passing in the other's mind just then, but his expression betrayed nothing more than interested anticipation. "We shall be entirely grateful to you if you will, Professor," he murmured. "I have no doubt of that, my dear sir. Now, to begin with: I presume that there are photographs of the persons mentioned in the newspapers as being in the Castle of Trelitz with the Prince on the last day that he was known to be there?" "Certainly; we should scarcely leave a simple preliminary like that neglected," smiled Nicol Hendry. "With the exception of the Frauelein Hulda von Tyssen, the Princess' Lady of the Bedchamber, all have been photographed for publication, and hers we have got through a private source. The Chief of each of our Departments has a copy of them, and I happen to have mine in my pocket now, if you would like to see them. The Princess, of course, you must have seen. She is in every photographer's window in the West End." "Oh yes, I have seen her. Who has not? She is a singularly beautiful woman. But I should very much like to see the others, if I may." The Chef de Bureau looked at him sharply as he took a small square morocco case out of his inner pocket and opened it. Going to a little table he spread out five small unmounted photographs upon it. He put two of them on one side, saying: "Those, of course, you know; they are the Prince and Princess. This one is Count Ulik von Kessner, High Chamberlain of Boravia; this, Captain Alexis Vollmar; and this is Frauelein von Tyssen." Franklin Marmion looked at them with much more than ordinary interest, for he recognised all five as clearly as though he had just left them in his own dining-room. "There are no suspicions attaching to any of these people, I suppose?" he said carelessly. "My dear Professor," replied Nicol Hendry a little coldly, "those who write stories about our profession always say that it is our invariable rule to suspect everybody, but we have a little common-sense, and we know the records of these ladies and gentlemen in the minutest detail from the Prince himself to Frauelein Hulda. We have not the slightest reason to suspect any of them." "Ah, just so," said the other musingly; "no, of course you wouldn't have, and, unfortunately, I cannot tell you why you should. But I'll tell you this: if you ever do find cause to suspect any of these persons, you will find that this group is not complete. It ought to contain the photograph of Prince Oscar Oscarovitch." "Prince Oscar Oscarovitch!" exclaimed Nicol Hendry, staring at him this time with wide-open eyes. "Why on earth should you----"