“Is that the real reason of your pious alarms?” asked Wilson, with a slight sneer.

The Irishman’s pale face blackened with a new passion.

“I have faced as many murderers in County Clare as you ever fought with in Clapham Junction, Mr. Cockney,” he said.

“Hush, please,” said Morton, sharply.  “Wilson, you have no kind of right to imply doubt of your superior’s conduct.  I hope you will prove yourself as courageous and trustworthy as he has always been.”

The pale face of the red-haired man seemed a shade paler, but he was silent and composed, and Sir Walter went up to Nolan with marked courtesy, saying, “Shall we go outside now, and get this business done?”

Dawn had lifted, leaving a wide chasm of white between a great gray cloud and the great gray moorland, beyond which the tower was outlined against the daybreak and the sea.

Something in its plain and primitive shape vaguely suggested the dawn in the first days of the earth, in some prehistoric time when even the colors were hardly created, when there was only blank daylight between cloud and clay.  These dead hues were relieved only by one spot of gold—­the spark of the candle alight in the window of the lonely tower, and burning on into the broadening daylight.  As the group of detectives, followed by a cordon of policemen, spread out into a crescent to cut off all escape, the light in the tower flashed as if it were moved for a moment, and then went out.  They knew the man inside had realized the daylight and blown out his candle.

“There are other windows, aren’t there?” asked Morton, “and a door, of course, somewhere round the corner?  Only a round tower has no corners.”

“Another example of my small suggestion,” observed Wilson, quietly.  “That queer tower was the first thing I saw when I came to these parts; and I can tell you a little more about it—­or, at any rate, the outside of it.  There are four windows altogether, one a little way from this one, but just out of sight.  Those are both on the ground floor, and so is the third on the other side, making a sort of triangle.  But the fourth is just above the third, and I suppose it looks on an upper floor.”

“It’s only a sort of loft, reached by a ladder, said Nolan.  “I’ve played in the place when I was a child.  It’s no more than an empty shell.”  And his sad face grew sadder, thinking perhaps of the tragedy of his country and the part that he played in it.

“The man must have got a table and chair, at any rate,” said Wilson, “but no doubt he could have got those from some cottage.  If I might make a suggestion, sir, I think we ought to approach all the five entrances at once, so to speak.  One of us should go to the door and one to each window; Macbride here has a ladder for the upper window.”

Mr. Horne Fisher languidly turned to his distinguished relative and spoke for the first time.

“I am rather a convert to the cockney school of psychology,” he said in an almost inaudible voice.