It was without avail—­save that he noticed Madeline Spencer and her escort were still at dinner.  They did not see him—­and he was very well content.  Later he would want a word with them—­particularly with her; and he preferred to meet her alone.  She was a very beautiful woman, and very alluring, and the time was, and not so long ago, when he would have gone far out of his way to meet her; but another face—­and business—­occupied him at present.  Moreover, the business had to do with Mrs. Spencer, and that shortly.  Therefore he was content to be patient.  Mrs. Clephane first.

So he went on to the private office and the manager.

“I’ve just taken another look over this floor,” he said; “Mrs. Clephane is not to be seen.”

“We paged her, also,” returned Banks; “and we’ve had every vacant room in the house examined without result.  Here’s the diagram; let us go over it, perhaps we can get a lead from it.  About half of the guests are personally known to the hotel; they are either permanent guests or have been coming here for a long time.  However, pick out any that you suspect and we’ll try to find a way to get into their rooms.  We are always at the service of the government, particularly the State Department.”

Harleston ran his eyes over the diagram, searching for Madeline Spencer.  It was barely possible that she was registered under one of her own names.  He found it at last—­or thought he had:  No. 717:—­Madame Cuthbert and maid.

“What do you know of her?” he asked, indicating No. 717.

“Nothing whatever, except that she seems to have plenty of money, and looks the lady.”

“When did she come?”

“Three days ago.”

“What is No. 717?”

“Two bedrooms, a parlour, and a bath.”

“I should like to know if she has had callers, and who they are; also, if the house detective knows anything of her movements?”

“One moment, sir,” said Banks—­

“And you might inquire also,” Harleston added, “as to the bald-headed man who is her companion this evening?”

“Very good, sir,” said Banks, and went out.

“I tell you there are quite too many women in this affair,” Harleston muttered—­and went back to inspecting the chart.

And the more he inspected, the more hopeless grew his task.  If Mrs. Clephane had been lured to one of the rooms, it would be next to impossible to find her.  There were a hundred well-dressed and quiet-mannered guests who seemed beyond suspicion; and yet it was in the room of one of these unobtrusive guests, who had never so much as looked at Mrs. Spencer, that Mrs. Clephane was held prisoner.  There was small hope—­none, indeed—­that a search of Madeline Spencer’s apartment would yield even a clue.  She was not such a bungler; though that she was the directing spirit in the entire affair he had not the least doubt.  Her photograph fixed the matter on her; and while he was quite sure she was not aware of the photograph, yet she was aware of the letter, had made a desperate effort to prevent its delivery, and now was making a final effort to prevent Mrs. Clephane from advising the French Ambassador of its loss.