Dr Hood replaced the silk hat carefully on the side table, and went across to the captive. He studied him intently, even moving him a little and half-turning him round by the shoulders, but he only answered:
“No; I think these ropes will do very well till your friends the police bring the handcuffs.”
Father Brown, who had been looking dully at the carpet, lifted his round face and said: “What do you mean?”
The man of science had picked up the peculiar dagger-sword from the carpet and was examining it intently as he answered:
“Because you find Mr Todhunter tied up,” he said, “you all jump to the conclusion that Mr Glass had tied him up; and then, I suppose, escaped. There are four objections to this: First, why should a gentleman so dressy as our friend Glass leave his hat behind him, if he left of his own free will? Second,” he continued, moving towards the window, “this is the only exit, and it is locked on the inside. Third, this blade here has a tiny touch of blood at the point, but there is no wound on Mr Todhunter. Mr Glass took that wound away with him, dead or alive. Add to all this primary probability. It is much more likely that the blackmailed person would try to kill his incubus, rather than that the blackmailer would try to kill the goose that lays his golden egg. There, I think, we have a pretty complete story.”
“But the ropes?” inquired the priest, whose eyes had remained open with a rather vacant admiration.
“Ah, the ropes,” said the expert with a singular intonation. “Miss MacNab very much wanted to know why I did not set Mr Todhunter free from his ropes. Well, I will tell her. I did not do it because Mr Todhunter can set himself free from them at any minute he chooses.”
“What?” cried the audience on quite different notes of astonishment.
“I have looked at all the knots on Mr Todhunter,” reiterated Hood quietly. “I happen to know something about knots; they are quite a branch of criminal science. Every one of those knots he has made himself and could loosen himself; not one of them would have been made by an enemy really trying to pinion him. The whole of this affair of the ropes is a clever fake, to make us think him the victim of the struggle instead of the wretched Glass, whose corpse may be hidden in the garden or stuffed up the chimney.”