Father Brown had resumed his monologue in an unruffled manner.
"You've been following the movements of a good many people in this business; you policemen were prodigiously interested in the movements of the poet, and the servant, and the Irishman. The man whose movements seem to have been rather forgotten is the dead man himself. His servant was quite honestly astonished at finding his master had returned. His master had gone to a great dinner of all the leaders of the legal profession, but had left it abruptly and come home. He was not ill, for he summoned no assistance; he had almost certainly quarrelled with some leader of the legal profession. It's among the leaders of that profession that we should have looked first for his enemy. He returned, and shut himself up in the bungalow, where he kept all his private documents about treasonable practices. But the leader of the legal profession, who knew there was something against him in those documents, was thoughtful enough to follow his accuser home; he also being in evening-dress, but with a pistol in his pocket. That is all; and nobody could ever have guessed it except for the mirror."
He seemed to be gazing into vacancy for a moment, and then added:
"A queer thing is a mirror; a picture frame that holds hundreds of different pictures, all vivid and all vanished for ever. Yet, there was something specially strange about the glass that hung at the end of that grey corridor under that green palm. It is as if it was a magic glass and had a different fate from others, as if its picture could somehow survive it, hanging in the air of that twilight house like a spectre; or at least like an abstract diagram, the skeleton of an argument. We could, at least, conjure out of the void the thing that Sir Arthur Travers saw. And by the way, there was one very true thing that you said about him."
"I'm glad to hear it," said Bagshaw with grim good-nature, "what was it?"
"You said," observed the priest, "that Sir Arthur must have some good reason for wanting to get Orm hanged."
A week later the priest met the police detective once more, and learned that the authorities had already been moving on the new lines of inquiry when they were interrupted by a sensational event.
"Sir Arthur Travers," began Father Brown.
"Sir Arthur Travers is dead," said Bagshaw, briefly.
"Ah!" said the other, with a little catch in his voice; "you mean that he——"