"Dampness of the place."

"Newness of the mortar, sir. That dog, by his wonderful instinct, knows that something is wrong behind here."

"Then he's a precious clever dog if he does, that's all I can say, because if you are right that inner cellar has been robbed and carefully built up again."

"This cellar has certainly been opened, sir, and built up again," said George, drawing his breath with a peculiar hiss as a curious suspicion seemed to flash through the dark parts of his brain.

Meanwhile the dog had watched every movement in silence, but only to grow excited again and stand barking.

"I'm of opinion," said the old lawyer dogmatically, "that Bruno smells a rat, and that you have discovered a mare's nest. Why, hang it, man, don't look at me in that ghastly manner. What's the matter?"

"I don't know, sir, but I have a horrible suspicion."

"Good heavens! My dear young friend, what do you mean?"

"I may be wrong, sir, but look at that dog."

"Yes, I believe he is going mad."

"I do not, sir. He has made a discovery."

"Yes, of rats," said the lawyer pettishly.

"I tell you once more, sir, I may be wrong; but Bruno seems to have found the clue I sought in vain."

"Clue?--what clue?"

"We have been searching for the man who called himself George Harrington."

"You have, sir. I have not."

"Well, I have. It may sound romantic and strange, but at the present moment I have a horrible dread that we have found him at last."

"What do you mean--where?"

For answer George Harrington pointed to the wall.

"What?" e.j.a.c.u.l.a.t.ed the old man, in a hoa.r.s.e whisper, and he caught at and held tightly by his companion's arm.

"I have had suspicions flashing about in a vague way in my brain, sir, but I could not arrange them. Now they begin to a.s.sume shape."

"Great heavens!"

"Look here, sir. This dog has been lying half dead ever since the disappearance of that man."

"Yes."

"What does he do as soon as he encounters Saul Harrington?"

"Fly at him."

"Yes. Why should he? Surely he has not been in the habit of trying to get at the throat of a relative and visitor of the house."

"That's quite true; certainly."

"You see the dog is as gentle with us as can be. Go to him yourself, and pat him."

"I hardly--Yes, I will," said the old man, mastering his dislike and dread; and, taking a couple of steps forward, he patted the dog's head.

"Why, Bruno, old dog, what's the matter?" he said in an awe-stricken whisper.

The dog swung round, looked at him, barked loudly, then rose up at him, placing his paws on his shoulders, and howled mournfully.

"There, you see," said George, laying his hand on the dog's head. "Mad?

No more than we are."

"But--but what has that to do with your theory of the man's disappearance?"

"Mr Hampton, I am not going to place it before you in words. My suspicion is that there has been foul play, and unless I am wrong, that man lies murdered behind yonder wall."

The old lawyer caught him by the arm, and looked in his face with his own turning quite white.

"You horrify me," he whispered in awe-stricken tones. "Surely it is impossible. Then you think that Mr Saul--"

"Never mind what I think," cried George Harrington sharply. "I only say that I have a horrible suspicion that there has been foul play."

"Then--then," cried the lawyer with trembling voice, "you--Oh, it is impossible!"

"No, sir; we have heard of such things before."

"Yes. Then, of course, we must have a search--the police."

"No, sir; we may be wrong."

"Yes, yes--of course," cried the old man eagerly--"Yes; you must be wrong."

"Look at that dog," whispered George.

The old man turned to see that the dog was snuffing about the wall, and ended by beginning to tear away the sawdust at the bottom.

"This is too horrible," whispered the old man, wiping his damp brow.

"What would you advise?"

"Finding out the truth, sir; and at once."

"But how. Whom would you trust?"

"Ourselves," said George sternly. "Let me see: the gardener is in the house. He must be got rid of, and we must not let the ladies or anyone know what we are going to do."

"But what we are going to do?"