In fact—this is absolutely private and mustn’t go any farther—he took his own life by shooting himself through the head.”

Owen raised his eyebrows. “What on earth made him do that, sir?”

“I imagine that it was partly remorse and partly because he considered it to be the best way out. If he hadn’t committed suicide he would have been arrested and tried for treason.”

“Treason!”

“I am afraid that is the only word one can use.” The speaker paused. “It was a bad business in every way. Medlicot was a bit of a genius in his own line, and for nearly a year before he died he had been conducting experimental work on some new gadget in connection with submarines. There is no need to enter into further details at the moment. All that matters is that the invention panned out very satisfactorily, and we were just congratulating ourselves that we were one up on the Boche when we learned through an agent that a complete copy of the plans had been sent over to Berlin, and that our Nazi friends were already hard at work on them. As you can well believe, this was something of a facer.”

Owen moistened his lips. “You mean that Medlicot had sold them?”

“There was no other conceivable explanation. Only four people had the necessary knowledge, and three of them were men whom it would be quite ridiculous to suspect. Besides”—Greystoke gave the faintest possible shrug—“we have a written confession which settles the matter beyond question. He must have posted it just before he shot himself.”

“It seems unbelievable.” Owen sat for an instant staring silently at his companion. “I ran across Medlicot once at Harwich, and he struck me as being a thoroughly decent fellow. What made him do such a damnable thing?”

“Ah! Now we are coming to the point. You know your way about the West End, Bradwell. I don’t want you to think that I have been delving impertinently into your private affairs, but I am informed that you are one of those fortunate mortals who are not entirely dependent on their pay, and that when you have a spot of leave you generally put in a day or two in Town. Is that correct?”

Owen nodded. “My father left me quite comfortably off, sir, and I have a good many friends in London. I like to look them up every now and then.”

“Quite so. Ever heard of a man named Mark Craig?”

“Mark Craig? Sounds vaguely familiar, but I can’t place him at the moment.”

“He runs a club in Grosvenor Street—very posh, expensive place where a crowd of rich people go to play poker. It’s called the Mayflower.”

“Oh, yes, I remember now, sir. I have never been there myself, but I have met blokes who belong to it.”

“You have met one, anyhow. Medlicot was a member. If he hadn’t enjoyed that distinction he would probably be alive now.”

“You mean he had been losing money there, sir?”

“Quite a lot, I imagine. We have no actual proof of that, but everything seems to point to it. I fancy that he was being threatened with exposure, and that in a moment of desperation he sold those plans in order to settle up his debts.”

“But couldn’t you find out for certain?”

“Not so easy, Bradwell. We did our utmost, of course, but in a case of suicide people are uncommonly shy about giving anything away. Don’t want to be dragged into a scandal.”

“Wasn’t there an official inquiry?”

“A very private one. You see, the mischief was done, and there was no sense in advertising the fact to the whole world. Besides, we had grounds for suspecting a certain highly placed gentleman at the German Embassy.