Somebody was knocking quietly at the door, and Sartoris had made no effort to move. That was the situation in which we left Sartoris and Berrington before Beatrice came. Nobody could have failed to notice that he was greatly disturbed and agitated. With a feeling that he was going to learn something, Berrington turned as if to leave the room.

"I am going to save you the trouble of going," he said.

Sartoris clasped his hands to his head. He was still throbbing and aching all over from the ill effect of the treatment accorded him by the Burmese visitors. Berrington had come down in the nick of time and saved him from a terrible fate, but Sartoris was not feeling in the least grateful. To a certain extent he was between the devil and the deep sea. Desperately as he was situated now, he could not afford to dismiss Berrington altogether. To do that would be to bring the authorities down upon him in double quick time. True, Berrington, out of his deep affection for Mary, might give him as much rope as possible. And again, Sartoris did not quite know how far Berrington was posted as to the recent course of events. True, Berrington suspected him of knowing something of the disappearance of the body of Sir Charles, but Sartoris did not see that he could prove anything.

But he did not want Berrington to go just yet, and he was still more anxious that the Colonel should not know who was knocking at the door. Unless his calculations were very wide of the mark, it was Beatrice Richford who was seeking admission. Sartoris would have given much to prevent those two meeting.

He smiled, though he was beside himself, almost, with passion. He seemed to have become very weak and impotent all at once. He would have to simulate an emotion that he did not possess. Once more there came the timid knock at the door.

"Berrington," he said desperately. "Do you believe that there is any good in me?"

The question was asked in almost a pleading voice. But Berrington was not in the least moved. He knew perfectly well what he had to deal with. Again, the knock at the door.

"I should say not a fragment," Berrington said critically. "I should say that you are utterly bad to the core. I have just saved you from a terrible fate which really ought to be a source of the greatest possible regret to me, but you are not in the least grateful. When that knock came for the first time, you looked at me with murder in your eyes. I am in your way now, I am possibly on the verge of an important discovery. If you could kill me with one look and destroy my body with another you would do it without hesitation. And that is the reason, my good friend, why I am going to the door."

"Don't," Sartoris implored. He had become mild and pleading. "You are quite wrong—Berrington; I once heard you say that there was good in everybody."

"Generally," Berrington admitted. "But you are an exception that proves the rule."

"Indeed I am not. There is good in me. I tell you and I am going to do a kind and disinterested action to-night. I swear that if you interfere you will be the cause of great unhappiness in a certain household in which I am interested. I implore you not to let your idle curiosity bring about this thing. I appeal to you as a gentleman."

In spite of himself Berrington was touched. He had never regarded Sartoris as anything of an actor, and he seemed to be in deadly earnest now. Was it just possible that the man had it in him to do a kindly thing? If so it seemed a pity to thwart him. Berrington looked fairly and squarely into the eyes of the speaker, but they did not waver in the least. The expression of Sartoris's face was one of hopelessness, not free altogether from contempt.

"I can't say any more," he said. "Open the door by all means, and spoil everything. It is in your hands to do so and curse your own vulgar curiosity afterwards. Call me mad if you like, but I had planned to do a kind thing to-night."

"So that you may benefit from it in the end?" Berrington suggested.

"Well, put it that way if you like," Sartoris said with fine indifference. "But it does not matter. You can sit down again. The knocker has gone, evidently."

But the door sounded again. Sartoris turned aside with a sigh. Despite his suspicions, Berrington felt that his conscience was troubling him. He would never forgive himself if he prevented a kind action being done to one who cruelly needed it. He rose and crossed the room.

"Let it be as you like," he said. "I will promise not to interfere. As soon as you have finished I should like to have a few words with you here. After that I shall feel free to depart."

Sartoris nodded, but the triumph that filled him found no expression on his face. Berrington was no better than a fool, after all; a few fair words had disarmed him. Sartoris would gain all he wanted and when that was done he would take good care that Berrington did not leave the house. The man was by no means at the end of his cunning resources yet. He moved his chair in the direction of the hall.

"You have made a very wise decision," he said. "And I thank you for having some confidence in me. Will you wait for me in the dining-room?"

Berrington intimated that he would go into the dining-room and smoke a cigar. He was free to depart now, but he was going to do nothing of the kind. Sartoris was likely to be engaged for some time, and meanwhile Berrington was able to make investigations. He was desirous of finding out the secret of the dining-room, the way in which things were changed there, and the like. Of course, it had all been done by human agency, and what one man can invent another can find out. There was not likely to be a more favourable opportunity.

Berrington stepped into the dining-room and closed the door behind him. But he closed it with his hand hard on the turned lock so that it should sound as if it had banged to, whereas, directly the handle was released it would fall open a little way. Berrington was not going to leave anything to chance, and he had no hesitation in playing the spy.

From where he stood he could hear the wheels of Sartoris's chair rattling over the parquet flooring of the hall, he heard the front door open, and the timid voice of a girl speaking. It did not sound like the voice of anybody with evil intent, and just for an instant it occurred to Berrington that perhaps his suspicions had been misplaced.

But only for an instant, until the voice spoke again. He had no difficulty now in recognising the voice as that of Beatrice Richford. Berrington was a little staggered, for he had not expected this. He had totally forgotten the letter, but it came flashing back to his mind now, and Mary's promise that no harm should come of it.

And yet Mary had either overestimated her powers or placed too low a value on the cunning of her brother. At any rate, there could be no doubt of the fact that the letter had been delivered, and that Beatrice was here in reply to it.

"Very good," Berrington said between his teeth. "I will see that no harm comes of this thing. Beatrice has been brought here to be pumped as to her father's papers and the like. Still, thanks to my little adventure to-night I have a pretty good idea what these scoundrels are after. I'll just go as far as the study and see that it is all right."

Berrington slipped off his boots and crept along the hall. So far as he could see all was quiet. There was a double door to the study, so that Berrington could not hear much, but the inner door had not been closed. It was only necessary to swing back the baize door to hear all that was taking place in the study.

But Berrington decided that he would leave that for the present. It mattered very little what Sartoris said to Beatrice, for the gist of the conversation could easily be gathered from the girl on some future occasion. But opportunities for examining that strange dining-room did not offer themselves at every hour, and Berrington made up his mind to make the best of it. He pulled on his boots again, and set to work.

For some time there was nothing to reward his search. The carpet appeared to be intact, the table a solid structure of mahogany. And yet there must be some means of moving that table up and down, much in the same way as the thing used to be done in the case of a certain French king and the lady of his affections.

But there was absolutely nothing here to show that anything of the kind had been done. Berrington removed the flowers and the table cloth and looked underneath. So far without success. He rapped in a reflective way on the solid legs and they gave back a clear ringing sound. With a smile of satisfaction, Berrington took a pocket knife from his vest.

Then he bent down and slightly scraped one of the solid-looking legs. The edge of the knife turned up and a thin strip of bright gold showed beneath the vanish. The first discovery had been made. The legs of the table were of hollow metal.

There was something to go on with at any rate. Dining tables do not have legs made of hollow metal for nothing. Berrington tried to push the table aside, so that he could tilt it up and see the base of the legs, but the structure refused to budge an inch. Here was discovery number two. The table was bolted solidly into the floor.

"We are getting on," Berrington whispered to himself. "It seems to me that I need not worry myself any further about the table itself, seeing that, so to speak, it is attached to the freehold. It is the floor that I have to look to."

But the floor appeared to be quite intact. There were no seams along the Turkey carpet. Berrington turned the carpet back as far as it would go, but nothing suspicious presented itself to his searching eye. As he dropped the carpet back his foot touched the curb of the fireplace, and one end slid along. It seemed a curious thing that one end of the old oak curb should work on a pivot, but so it did, and Berrington pushed it as far as it would go. An instant later and he jumped nimbly into the fireplace.

It was just as well he did so, for the whole floor was slowly fading away, just up to the edge of the carpet, leaving the brown boards around intact. By accident more than anything else Berrington had stumbled on the secret. The pressure of a foot on the curb had set some hidden lever in motion; the clever machinery was doing the rest.

Standing in the fireplace Berrington watched for the effect. The floor sank away as if working on a pivot; it came around with the other side up, and on the other side was a carpet quite similar to the first in pattern. There was also another table which came up on a swinging balance so that everything on it would not be disturbed.

"Well, this is a pretty fine Arabian Nights' form of entertainment," Berrington muttered. "I wonder if I can keep the thing half suspended like that whilst I examine the vault beneath. I suppose if I push the lever half back it will remain stationary. That's it!" The lever being pushed half back caused the machinery to lock so that the floor was all on the slant. There was a kind of space below which appeared to be paved and bricked like a well. Into this the full rays of the electric light shone. It was easy to jump down there and examine the place, and Berrington proceeded to do so.

So far as he could see there was a heap of old clothes huddled together in a corner. In an idle way Berrington turned them over. A collar fell out from the rest and Berrington took it up—a white collar that had been worn for some little time. Berrington started as his eye fell on the name plainly set out in marking ink.

"Great Scott," he cried. "Why it is one of Sir Charles Darryll's!"