good heavens!" called out Miss MacNab, "aren't you going to untie the man first?"
"I say 'old' with intention, though not with certainty" continued the expositor; "my reason for it might seem a little far-fetched. The hair of human beings falls out in very varying degrees, but almost always falls out slightly, and with the lens I should see the tiny hairs in a hat recently worn. It has none, which leads me to guess that Mr Glass is bald. Now when this is taken with the high-pitched and querulous voice which Miss MacNab described so vividly (patience, my dear lady, patience), when we take the hairless head together with the tone common in senile anger, I should think we may deduce some advance in years. Nevertheless, he was probably vigorous, and he was almost certainly tall. I might rely in some degree on the story of his previous appearance at the window, as a tall man in a silk hat, but I think I have more exact indication. This wineglass has been smashed all over the place, but one of its splinters lies on the high bracket beside the mantelpiece. No such fragment could have fallen there if the vessel had been smashed in the hand of a comparatively short man like Mr Todhunter."
"By the way," said Father Brown, "might it not be as well to untie Mr Todhunter?"
"Our lesson from the drinking-vessels does not end here," proceeded the specialist. "I may say at once that it is possible that the man Glass was bald or nervous through dissipation rather than age. Mr Todhunter, as has been remarked, is a quiet thrifty gentleman, essentially an abstainer. These cards and wine-cups are no part of his normal habit; they have been produced for a particular companion. But, as it happens, we may go farther. Mr Todhunter may or may not possess this wine-service, but there is no appearance of his possessing any wine. What, then, were these vessels to contain? I would at once suggest some brandy or whisky, perhaps of a luxurious sort, from a flask in the pocket of Mr Glass. We have thus something like a picture of the man, or at least of the type: tall, elderly, fashionable, but somewhat frayed, certainly fond of play and strong waters, perhaps rather too fond of them. Mr Glass is a gentleman not unknown on the fringes of society."
"Look here," cried the young woman, "if you don't let me pass to untie him I'll run outside and scream for the police."
"I should not advise you, Miss MacNab," said Dr Hood gravely, "to be in any hurry to fetch the police. Father Brown, I seriously ask you to compose your flock, for their sakes, not for mine. Well, we have seen something of the figure and quality of Mr Glass; what are the chief facts known of Mr Todhunter? They are substantially three: that he is economical, that he is more or less wealthy, and that he has a secret. Now, surely it is obvious that there are the three chief marks of the kind of man who is blackmailed. And surely it is equally obvious that the faded finery, the profligate habits, and the shrill irritation of Mr Glass are the unmistakable marks of the kind of man who blackmails him. We have the two typical figures of a tragedy of hush money: on the one hand, the respectable man with a mystery; on the other, the West-end vulture with a scent for a mystery. These two men have met here today and have quarrelled, using blows and a bare weapon."
"Are you going to take those ropes off?" asked the girl stubbornly.
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."
There was a rather depressed silence; the room was darkening, the sea-blighted boughs of the garden trees looked leaner and blacker than ever, yet they seemed to have come nearer to the window. One could almost fancy they were sea-monsters like krakens or cuttlefish, writhing polypi who had crawled up from the sea to see the end of this tragedy, even as he, the villain and victim of it, the terrible man in the tall hat, had once crawled up from the sea. For the whole air was dense with the morbidity of blackmail, which is the most morbid of human things, because it is a crime concealing a crime; a black plaster on a blacker wound.
The face of the little Catholic priest, which was commonly complacent and even comic, had suddenly become knotted with a curious frown. It was not the blank curiosity of his first innocence. It was rather that creative curiosity which comes when a man has the beginnings of an idea. "Say it again, please," he said in a simple, bothered manner; "do you mean that Todhunter can tie himself up all alone and untie himself all alone?"
"That is what I mean," said the doctor.
"Jerusalem!" ejaculated Brown suddenly, "I wonder if it could possibly be that!"
He scuttled across the room rather like a rabbit, and peered with quite a new impulsiveness into the partially-covered face of the captive. Then he turned his own rather fatuous face to the company. "Yes, that's it!" he cried in a certain excitement. "Can't you see it in the man's face? Why, look at his eyes!"
Both the Professor and the girl followed the direction of his glance. And though the broad black scarf completely masked the lower half of Todhunter's visage, they did grow conscious of something struggling and intense about the upper part of it.
"His eyes do look queer," cried the young woman, strongly moved. "You brutes; I believe it's hurting him!"
"Not that, I think," said Dr Hood; "the eyes have certainly a singular expression. But I should interpret those transverse wrinkles as expressing rather such slight psychological abnormality—"
"Oh, bosh!" cried Father Brown: "can't you see he's laughing?"
"Laughing!" repeated the doctor, with a start; "but what on earth can he be laughing at?"
"Well," replied the Reverend Brown apologetically, "not to put too fine a point on it, I think he is laughing at you. And indeed, I'm a little inclined to laugh at myself, now I know about it."
"Now
