“As you have truly remarked,” replied Joan, with ugly calm, “your clerk is a very respectable young man, who knows the nature of an oath; and he will swear in any court that I was up in your office arranging some typewriting work for five minutes before and five minutes after my sister fell.  Mr. Flambeau will tell you that he found me there.”

There was a silence.

“Why, then,” cried Flambeau, “Pauline was alone when she fell, and it was suicide!”

“She was alone when she fell,” said Father Brown, “but it was not suicide.”

“Then how did she die?” asked Flambeau impatiently.

“She was murdered.”

“But she was alone,” objected the detective.

“She was murdered when she was all alone,” answered the priest.

All the rest stared at him, but he remained sitting in the same old dejected attitude, with a wrinkle in his round forehead and an appearance of impersonal shame and sorrow; his voice was colourless and sad.

“What I want to know,” cried Kalon, with an oath, “is when the police are coming for this bloody and wicked sister.  She’s killed her flesh and blood; she’s robbed me of half a million that was just as sacredly mine as—­”

“Come, come, prophet,” interrupted Flambeau, with a kind of sneer; “remember that all this world is a cloudland.”

The hierophant of the sun-god made an effort to climb back on his pedestal.  “It is not the mere money,” he cried, “though that would equip the cause throughout the world.  It is also my beloved one’s wishes.  To Pauline all this was holy.  In Pauline’s eyes—­”

Father Brown suddenly sprang erect, so that his chair fell over flat behind him.  He was deathly pale, yet he seemed fired with a hope; his eyes shone.

“That’s it!” he cried in a clear voice.  “That’s the way to begin.  In Pauline’s eyes—­”

The tall prophet retreated before the tiny priest in an almost mad disorder.  “What do you mean?  How dare you?” he cried repeatedly.

“In Pauline’s eyes,” repeated the priest, his own shining more and more.  “Go on—­in God’s name, go on.  The foulest crime the fiends ever prompted feels lighter after confession; and I implore you to confess.  Go on, go on—­in Pauline’s eyes—­”

“Let me go, you devil!” thundered Kalon, struggling like a giant in bonds.  “Who are you, you cursed spy, to weave your spiders’ webs round me, and peep and peer?  Let me go.”

“Shall I stop him?” asked Flambeau, bounding towards the exit, for Kalon had already thrown the door wide open.

“No; let him pass,” said Father Brown, with a strange deep sigh that seemed to come from the depths of the universe.  “Let Cain pass by, for he belongs to God.”

There was a long-drawn silence in the room when he had left it, which was to Flambeau’s fierce wits one long agony of interrogation.  Miss Joan Stacey very coolly tidied up the papers on her desk.