"Ah," said Granby thoughtfully, "the legal negotiations! You mean, of course, that the real old baronet would have negotiated very differently.
"He would have told you plainly that the Captain would never get a penny," said Father Brown. "The plot, queer as it sounds, was really the only way of preventing his telling you so. But I want you to appreciate the cunning of what the fellow did tell you. His plan answered several purposes at once. He was being blackmailed by these Russians for some villainy; I suspect for treason during the war. He escaped from them at a stroke, and probably sent them chasing off to Riga after him. But the most beautiful refinement of all was that theory he enunciated about recognizing his son as an heir, but not as a human being. Don't you see that while it secured the post obit, it also provided some sort of answer to what would soon be the greatest difficulty of all?"
"I see several difficulties," said Granby; "which one do you mean?"
"I mean that if the son was not even disinherited, it would look rather odd that the father and son never met. The theory of a private repudiation answered that. So there only remained one difficulty, as I say, which is probably perplexing the gentleman now. How on earth is the old man to die?"
"I know how he ought to die," said Granby.
Father Brown seemed to be a little bemused, and went on in a more abstracted fashion.
"And yet there is something more in it than that," he said. "There was something about that theory that he liked in a way that is more—well, more theoretical. It gave him an insane intellectual pleasure to tell you in one character that he had committed a crime in another character—when he really had. That is what I mean by the infernal irony; by the joke shared with the Devil. Shall I tell you something that sounds like what they call a paradox? Sometimes it is a joy in the very heart of hell to tell the truth. And above all, to tell it so that everybody misunderstands it. That is why he liked that antic of pretending to be somebody else, and then painting himself as black—as he was. And that was why my niece heard him laughing to himself all alone in the picture gallery."
Granby gave a slight start, like a person brought back to common things with a bump.
"Your niece," he cried. "Didn't her mother want her to marry Musgrave? A question of wealth and position, I suppose."
"Yes," said Father Brown dryly; "her mother was all in favour of a prudent marriage."