“Come along, Fisher,” called out Sir Walter from below, when the others had regained the floor.  “We must consider whether we’ll pull the whole place to pieces to see what it’s made of.”

“I’m coming in a minute,” said the voice from the ledge above their heads, a voice somewhat suggestive of an articulate yawn.

“What are you waiting for?” asked Sir Walter, impatiently.  “Can you see anything there?”

“Well, yes, in a way,” replied the voice, vaguely.  “In fact, I see it quite plain now.”

“What is it?” asked Wilson, sharply, from the table on which he sat kicking his heels restlessly.

“Well, it’s a man,” said Horne Fisher.

Wilson bounded off the table as if he had been kicked off it.  “What do you mean?” he cried.  “How can you possibly see a man?”

“I can see him through the window,” replied the secretary, mildly.  “I see him coming across the moor.  He’s making a bee line across the open country toward this tower.  He evidently means to pay us a visit.  And, considering who it seems to be, perhaps it would be more polite if we were all at the door to receive him.”  And in a leisurely manner the secretary came down the ladder.

“Who it seems to be!” repeated Sir Walter in astonishment.

“Well, I think it’s the man you call Prince Michael,” observed Mr. Fisher, airily.  “In fact, I’m sure it is.  I’ve seen the police portraits of him.”

There was a dead silence, and Sir Walter’s usually steady brain seemed to go round like a windmill.

“But, hang it all!” he said at last, “even supposing his own explosion could have thrown him half a mile away, without passing through any of the windows, and left him alive enough for a country walk—­even then, why the devil should he walk in this direction?  The murderer does not generally revisit the scene of his crime so rapidly as all that.”

“He doesn’t know yet that it is the scene of his crime,” answered Horne Fisher.

“What on earth do you mean?  You credit him with rather singular absence of mind.”

“Well, the truth is, it isn’t the scene of his crime,” said Fisher, and went and looked out of the window.

There was another silence, and then Sir Walter said, quietly:  “What sort of notion have you really got in your head, Fisher?  Have you developed a new theory about how this fellow escaped out of the ring round him?”

“He never escaped at all,” answered the man at the window, without turning round.  “He never escaped out of the ring because he was never inside the ring.  He was not in this tower at all, at least not when we were surrounding it.”

He turned and leaned back against the window, but, in spite of his usual listless manner, they almost fancied that the face in shadow was a little pale.

“I began to guess something of the sort when we were some way from the tower,” he said.  “Did you notice that sort of flash or flicker the candle gave before it was extinguished?  I was almost certain it was only the last leap the flame gives when a candle burns itself out.  And then I came into this room and I saw that.”