Wandering from side to side of the library, he presently found himself standing still before the mantelpiece and studying a photograph in a silver frame which occupied the centre of the shelf.  It was the photograph of an unusually pretty girl; that is to say, of a girl whose beauty was undeniable, but who belonged to a type widely removed from that of the ordinary good-looking Englishwoman.

The outline of her face was soft and charming, and there was a questioning look in her eyes which was alluring and challenging.  Her naive expression was palpably a pose, and her slightly parted lips promised laughter.  She possessed delightfully wavy hair and her neck and one shoulder, which were bare, had a Grecian purity.  Harley discovered himself to be smiling at the naive lady of the photograph.

“Presumably ’Miss Phil’,” he said aloud.

He removed his gaze with reluctance from the fascinating picture, and dropping into the big lounge chair, he lighted a cigarette.  He had just placed the match in an ash tray when he heard Sir Charles’s voice in the lobby, and a moment later Sir Charles himself came hurrying into the library.  His expression was so peculiar that Harley started up immediately, perceiving that something unusual had happened.

“My dear Mr. Harley,” began Sir Charles, “in the first place pray accept my apologies—­”

“None are necessary,” Harley interrupted.  “Your excellent housekeeper has entertained me vastly.”

“Good, good,” muttered Sir Charles.  “I am obliged to Mrs. Howett,” and it was plainly to be seen that his thoughts were elsewhere.  “But I have to relate a most inexplicable occurrence—­inexplicable unless by some divine accident the plan has been prevented from maturing.”

“What do you mean, Sir Charles?”

“I was called ten minutes ago by someone purporting to be the servant of Mr. Chester Wilson, that friend and neighbour whom I have been attending.”

“So your butler informed me.”

“My dear sir,” cried Sir Charles, and the expression in his eyes grew almost wild, “no one in Wilson’s house knew anything about the matter!”

“What!  It was a ruse?”

“Palpably a ruse to get me away from home.”

Harley dropped his cigarette into the ash tray beside the match, where, smouldering, it sent up a gray spiral into the air of the library.  Whether because of his words or because of the presence of the man himself, the warning, intuitive finger had again touched Paul Harley.  “You saw or heard nothing on your way across the square to suggest that any one having designs on your safety was watching you?”

“Nothing.  I searched the shadows most particularly on my return journey, of course.  For the thing cannot have been purposeless.”

“I quite agree with you,” said Paul Harley, quietly.

Between the promptings of that uncanny sixth sense of his and the working of the trained deductive reasoning powers, he was momentarily at a loss.  Some fact, some episode, a memory, was clamouring for recognition, while the intuitive, subconscious voice whispered:  “This man is in danger; protect him.”  What was the meaning of it all?  He felt that a clue lay somewhere outside the reach of his intelligence, and a sort of anger possessed him because of his impotence to grasp it.