“Tell me only what you think necessary,” said I.

He thanked me.  “That is what I wanted,” he said.  “Well, all of a sudden, when we had found out a way and Urquhart was discussing it, he pulled himself up in the middle of a sentence, and with his eyes fixed on the other—­a most curious look it was—­he waited while you could count ten, and, ‘No,’ says he, ’I’ll not fight you at once’—­for we had been arranging something of the sort—­’not to-night, anyway, nor to-morrow,’ he says.  ’I’ll fight you; but I won’t have your blood on my head in that way.’  Those were his words.  I have no notion what he meant; but he kept repeating them, and would not explain, though Mackenzie tried him hard and was for shooting across the table.  He was repeating them when the Major interrupted us and called him up.”

“He has behaved ill from the first,” said I.  “To me the whole affair begins to look like an abominable plot against Mackenzie.  Certainly I cannot entertain a suspicion of his guilt upon a bare assertion which Urquhart declines to back with a tittle of evidence.”

“The devil he does!” mused Captain Murray.  “That looks bad for him.  And yet, sir, I’d sooner trust Urquhart than Mackenzie, and if the case lies against Urquhart—­”

“It will assuredly break him,” I put in, “unless he can prove the charge, or that he was honestly mistaken.”

“Then, sir,” said the Captain, “I’ll have to show you this.  It’s ugly, but it’s only justice.”

He pulled a sovereign from his pocket and pushed it on the writing-table under my nose.

“What does this mean?”

“It is a marked one,” said he.

“So I perceive.”  I had picked up the coin and was examining it.

“I found it just now,” he continued, “in the room below.  The upsetting of the table had scattered Mackenzie’s stakes about the floor.”

“You seem to have a pretty notion of evidence,” I observed sharply.  “I don’t know what accusation this coin may carry; but why need it be Mackenzie’s?  He might have won it from Urquhart.”

“I thought of that,” was the answer.  “But no money had changed hands.  I enquired.  The quarrel arose over the second deal, and as a matter of fact Urquhart had laid no money on the table, but made a pencil-note of a few shillings he lost by the first hand.  You may remember, sir, how the table stood when you entered.”

I reflected.  “Yes, my recollection bears you out.  Do I gather that you have confronted Mackenzie with this?”

“No.  I found it and slipped it quietly into my pocket.  I thought we had trouble enough on hand for the moment.”

“Who marked this coin?”

“Young Fraser, sir, in my presence.  He has been losing small sums, he declares, by pilfering.  We suspected one of the orderlies.”

“In this connection you had no suspicion of Mr. Mackenzie?”