"All the same, I really must get it," Claire persisted. "I am sorry that you do not recall the piece at all. If you will come into the drawing-room with me, and can spare me a few minutes, I will strum the piece over to you. It so fascinated me that I committed it to memory. Do come along for a moment."

Anstruther laughed, as Jack thought, rather uneasily. He tried skilfully enough to divert the conversation into another channel, but Claire's enthusiasm refused to be baffled. Anstruther's face darkened for a moment, and there was a look in his eyes that boded ill to somebody. He rose and walked across towards the door, and up the stairs in the direction of the drawing-room..

"Very well, if you must," he said. "I can give you ten minutes. I dare say it is some silly trifle that I have heard somewhere without recognizing its source."

Claire seated herself at the piano, and played the little piece off with both brilliancy and feeling. As a matter of fact, she had been practicing it several times during the afternoon until she had it absolutely correct. The slow, mournful chords died away at length, and then Claire turned to her guardian with a smile.

"That is it," she said . "That is the little piece that so fascinated me last night. Surely you can tell me the name of it and where it came from?"

The question was apparently simple enough, but Anstruther appeared to be absolutely incapable of answering it.

"Do you mean to say you could forget a thing like that?" Claire protested. "It seems to me impossible."

"Perhaps it made less impression upon me than it did you," Anstruther muttered. "I haven't the slightest recollection of playing it myself. In fact----"

Anstruther broke off in absolute confusion. The incident, trivial as it seemed, had upset him altogether. He was about to betray himself by saying that he had never heard the piece before, and that it had no place amongst his music; but he pulled himself up just in time. He bitterly blamed Padini's carelessness. It was no part of the programme for his double to give him anything but pieces of music with which he was absolutely familiar. What he might have said and done was frustrated by the appearance of Serena, who announced that a gentleman down-stairs desired to see Mr. Anstruther.

Jack felt his pulses beating a little faster, for he had had no reason to inquire who the stranger was. Serena's eyes were demure and downcast as usual as she replied to Anstruther's question that the gentleman down-stairs was none other than Inspector Bates, of Scotland Yard. Only just for an instant did Anstruther falter and turn pale, then he was absolutely himself again. He almost wished now that he had not waited so long. He had his ingenious alibi, it was true, but even that might fail. There were so many meshes in the nets of Scotland Yard. In a calm, even voice he ordered Serena to show the stranger up-stairs. Bates came at length, a little pallid and bruised, but otherwise little worse for his last night's adventure.