“That was what Boyle did; he barely touched the thing, and it went round as easily as the world goes round.  Yes, very much as the world goes round, for the hand that turned it was not his.  God, who turns the wheel of all the stars, touched that wheel and brought it full circle, that His dreadful justice might return.”

“I am beginning,” said Grayne, slowly, “to have some hazy and horrible idea of what you mean.”

“It is very simple,” said Fisher, “when Boyle straightened himself from his stooping posture, something had happened which he had not noticed, which his enemy had not noticed, which nobody had noticed.  The two coffee cups had exactly changed places.”

The rocky face of Grayne seemed to have sustained a shock in silence; not a line of it altered, but his voice when it came was unexpectedly weakened.

“I see what you mean,” he said, “and, as you say, the less said about it the better.  It was not the lover who tried to get rid of the husband, but—­the other thing.  And a tale like that about a man like that would ruin us here.  Had you any guess of this at the start?”

“The bottomless well, as I told you,” answered Fisher, quietly; “that was what stumped me from the start.  Not because it had anything to do with it, because it had nothing to do with it.”

He paused a moment, as if choosing an approach, and then went on:  “When a man knows his enemy will be dead in ten minutes, and takes him to the edge of an unfathomable pit, he means to throw his body into it.  What else should he do?  A born fool would have the sense to do it, and Boyle is not a born fool.  Well, why did not Boyle do it?  The more I thought of it the more I suspected there was some mistake in the murder, so to speak.  Somebody had taken somebody there to throw him in, and yet he was not thrown in.  I had already an ugly, unformed idea of some substitution or reversal of parts; then I stooped to turn the bookstand myself, by accident, and I instantly knew everything, for I saw the two cups revolve once more, like moons in the sky.”

After a pause, Cuthbert Grayne said, “And what are we to say to the newspapers?”

“My friend, Harold March, is coming along from Cairo to-day,” said Fisher.  “He is a very brilliant and successful journalist.  But for all that he’s a thoroughly honorable man, so you must not tell him the truth.”

Half an hour later Fisher was again walking to and fro in front of the clubhouse, with Captain Boyle, the latter by this time with a very buffeted and bewildered air; perhaps a sadder and a wiser man.

“What about me, then?” he was saying.  “Am I cleared?  Am I not going to be cleared?”

“I believe and hope,” answered Fisher, “that you are not going to be suspected.  But you are certainly not going to be cleared.  There must be no suspicion against him, and therefore no suspicion against you.  Any suspicion against him, let alone such a story against him, would knock us endways from Malta to Mandalay.  He was a hero as well as a holy terror among the Moslems.  Indeed, you might almost call him a Moslem hero in the English service.  Of course he got on with them partly because of his own little dose of Eastern blood; he got it from his mother, the dancer from Damascus; everybody knows that.”