It was plainly evident that Bates believed in his ability to solve the problem. Anstruther had quite thrown the mask off by this time, and stood glaring vindictively at the inspector. It was absolutely maddening to a man of his ability to be caught in a sorry trap like this. One of the strongest points in Anstruther's schemes was the fact that hitherto he had always been on the side of the police. He had been regarded as one of them, so to speak, so that many of his ingenious plots had been guided solely by the action of the authorities. It had never once occurred to him that he might have been an object of suspicion at Scotland Yard.

"You might just as well take it quietly," Bates said. "We know the whole thing from start to finish. It will go a great deal easier with you if you give us all the information that lies in your power and save us trouble."

"That is the usual course, I believe," Anstruther sneered. "But you have a different man to deal with in me. I am quite at a loss to understand what you are doing here at all."

Bates shrugged his shoulders, and walked in the direction of the door. He had no difficulty in seeing that Anstruther had made up his mind to see this thing through to the bitter end. Therefore, it was quite useless to try and get him to see matters in a reasonable light. Anstruther stood there, white, silent, and furious, whilst all the time the amazing music was going on in the study.

Mysterious as the whole thing appeared to be, there was almost an element of farce in it. Here was the very man who relied upon his devotion to his violin to save him in the hour of danger, actually listening, so to speak, to his own performance. He had little doubt what Bates meant to do, for the latter was already half-way down the stairs on his way to the study. With a sudden impulse Anstruther followed. He passed Bates with a rapid stride, and, standing with his back to the study door, defied the inspector to enter.

"You do not seem to understand," Bates said. "The warrant I have for your arrest gives me the right of searching the whole house. If you persist in this absurd conduct, I shall have to call my men in and remove you by force."

The two men faced one another, both angry and excited, and ready to fly at one another's throats. And yet the whole time their ears were filled with the beautiful melody of the music, as it floated from the room behind.

"What are we going to do?" Claire asked. She was standing with Jack at the top of the staircase. "Is it not time that we declared ourselves?"

Jack whispered to Claire to remain where she was a moment, and slipped out of the house into the garden unperceived. It had suddenly occurred to him that perhaps the window leading from the study to the garden was unfastened. He recollected that this was the means by which Anstruther left and returned to the house. It would have been imprudent on the latter's part to use the front door, and there was not much risk in leaving the study window unlatched.

It was just as Jack had expected. The long French window gave to his touch, and a moment later he was in the room. As it happened on the previous occasion, he could see not the faintest trace of any mechanism by means of which the melody was conveyed from the Great Metropolitan Hotel to Panton Square. And yet the whole room was flooded with it; rising and falling in triumphant strains, as if mocking the intellect of a man who had brought this wonderful result about. But there was no time to speculate on that, no time for close investigation. On the other side of the door the voices of Anstruther and Bates were rising to a still more angry pitch, and Claire's tones of expostulation came to Jack's ears. As he crossed the room he could see that the key was in the door. He flung it open, and Anstruther came staggering backward into the room, closely followed by the detective.

"You can see that the game is up," the latter said coolly. "Why not make a clean breast of it? I shall find out how this is done, if I have to pull down the house to do it."

Anstruther smiled in a scornful kind of way, and flung himself doggedly into a seat. He bade Bates do his worst, and prophesied that the police would suffer for this indignity. But Bates was not listening. He was pacing rapidly round the room with his ear to the wall, as if scenting out some clue to the mystery. A moment later, and there came into the room the form of Serena.

One glance at her sufficed to show that she was not the Serena whom Jack had known so long. The demure, downcast eyes were no longer seeking the floor as of old; there was no shrinking and timidity on the part of the woman now. She was changed almost beyond recognition. She walked with a firm, elastic tread, her shoulders were thrown back, and her head uplifted fearlessly. From under his heavy brows Anstruther glanced at her suspiciously.

"Go away," he commanded hoarsely. "How dare you force yourself in here like this! Go, woman."

But the tones of command had evidently lost their power. There was no shrinking on Serena's part. She advanced into the middle of the room as if the place belonged to her.

"No, no," she cried in tones as clear and ringing as Anstruther's own. "Your power has gone forever. For three long patient years I have waited for this moment. God only knows what my life has been, and what a hell your cruelty has created for me. But the cord is broken now. Only to-night I have learned the truth. I have been your good and faithful servant; I have stooped to do your hateful work; I have been the ally of criminals--of your creature Redgrave, amongst others; and all because I thought you held my life in the hollow of your hand."

"Tell them the story of your boy," Anstruther sneered.

"I will tell them the truth," Serena cried. "You said you could hang me if you liked. You pretended that in my delirium I had taken the life of my darling child. You were shielding a murderess, as I thought. But it was a black and cruel lie. Give me back my wasted years, you coward; give me back my sleepless nights and dreary days. But, thank God, that time has passed. My boy is alive--alive! He is safe in the house at present!"

Anstruther started as if some loathsome insect had stung him, then dropped sullenly back in his seat again. Bates turned to Serena and called her attention to the music.

"You seem to be in a communicative mood to-night," he said. "You need not fear any one for the future--Redgrave, or anybody else. I understand this last scoundrel is safe in the hands of the Ne............