There was a smile on Slight's face, as if he rather enjoyed the situation. After all was said and done, the culprit had been successful in bringing about the thing the old butler most desired. Fortunately no harm had been done to the house; there was nothing the matter beyond the damage caused by smoke and water, nothing that the work of a day or two could not put right. At the same time this attempt to destroy the house had been the means of removing from it the trio whose presence had been so great a humiliation. The police had cleared everybody out of the house, indeed the Hall was likely to remain empty now till they had investigated the causes of the fire.

"It might have been worse, sir," Slight whispered to Ralph. "It's a good way of getting rid of those fellows till Sir George is ready to pack them off altogether. Whoever did this was a sort of friend of ours."

Ralph started. Slight's suggestion had given him a sudden idea.

"That may be," he said, "but you will admit that the experiment is a risky one. The place might have been utterly destroyed. Still, it is yet to be proved that this is the work of an incendiary. I can hardly believe that it is."

The inspector led the way to the Hall. So far as the eye of a novice could judge, it was here that the fire had burst out. The floor was black and scarred and a few beams were still hot from the effects of the flames. The floor was littered with some crisp ashes.

"Now I want to call your attention to this, Sir George," the inspector said. "Nothing has been destroyed here, nothing but the floor and a portion of the ceiling. There must have been a very fierce blaze here, and yet there is nothing for the flames to feed on. Then where did all those crisp short ashes come from? See what a pile there is of them! What was it that burnt here so fiercely?"

"It certainly is a strange thing," Sir George murmured.

"Very strange, sir.' There was nothing left on the hall floor last night, I suppose? No packing cases or anything of that kind, Sir George?"

"There was not," Slight exclaimed. "I can answer for that, nothing whatever."

"Which renders my suspicions all the more certain," the official went on. "The short crisp ashes represented straw, a large bundle of straw dumped down on the floor and set fire to by some person or other. Please look at this."

The speaker stooped down and gathered up a handful of the crisp ashes, smoothing them out on the palm of his hand. At intervals there were yellow shining specks in the grains.

"Will you kindly look closely?" he said. "Amongst the charred mass you can plainly see specks of straw that have escaped the fire. It seems to me an amazing thing that anybody could carry straw into the house like this without being found out. But there it is, and there is an end of it. You are quite sure as to the straw, Sir George?"

"Quite," Dashwood muttered. "Most amazing. We did not go to bed till very late, which makes it all the more remarkable. It must have been practically daylight before the miscreant could have begun to work."

"It certainly is a novelty," the Inspector replied, "but I want to convince you fully that I am right in my conclusion. You will see that parts of the ashes, very minute parts, are plastered together as if they were wet. Also you will see that the floor has been burnt in a kind of channel nearly as far as the door. It is only a narrow channel, but at the same time it is perfectly well defined. Now, what caused the floor to burn in that erratic manner? I am going to tell you. Let us follow that track up as far as the door. There is a large stone with little cracks at the side into which a liquid of some kind has fallen or run rather."

The speaker bent down and rolled a scrap of paper into the moisture which lay shining in the crack of the stone. Then he handed the paper to Sir George.

"Will you kindly smell that, sir," he asked, "and tell me what you make of it?"

"No trouble at all about that," Dashwood exclaimed; "the stuff is paraffin beyond a doubt."

"Precisely. The straw was dumped on the floor and then saturated with paraffin. If the straw was slightly damp, that would account for the dense quantity of smoke. The paraffin ran into little ripples over the floor, which accounts for the strange track of the flames. But we can ascertain that to a certainty."

A question or two being asked, it was discovered that a large can of petroleum was missing from one of the toolsheds. A little later the empty tin was discovered in one of the flower-beds. The discussion was at its height when Mary appeared. She looked very pale and shaky, otherwise she maintained her self-possession. But as she listened to the strange story it seemed to Ralph Darnley that she ............