n on to Sir Lyster in bewilderment.

"Perhaps, Sage----" suggested Colonel Walton.

"You'd better tell the story, Sage, as Colonel Walton suggests," said
Mr. Llewellyn John.

"There is an official report in preparation," said Colonel Walton.

Mr. Llewellyn John nodded.

In the course of the next half-hour Malcolm Sage kept his hearers in a
state of breathless interest by the story of the coming and going of
John Dene, as known to Department Z.

"I gave Mr. Dene the credit of being possessed of more than the
ordinary amount of what he calls 'head-filling,'" began Sage, "but I
didn't realise at first that he possessed a twin brother; but I'll
begin at the beginning."

"When you turned over the matter to Department Z.," continued Malcolm
Sage, "we made exhaustive inquiries and discovered that the Huns were
determined to prevent the _Destroyer_ from putting to sea, and they
were prepared at any cost to stop Mr. Dene from going north. In Canada
and on the way over they made attempts upon his life; but then, as so
frequently happens, they became the victims of divided councils. They
wanted the plans. Thanks to, er--certain happenings they learned that
the _Destroyer_ would not sail without Mr. Dene."

"How?" interpolated Mr. Llewellyn John

"They obtained the guarantee."

"I remember," said Mr. Llewellyn John, "it was stolen."

"Mr. Dene used to leave his safe open with such papers in it as he
wanted the enemy to see. That's what he meant when on one occasion he
said, 'If you've got a hungry dog feed it.'"

Sir Bridgman North laughed, Sir Lyster turned to him reproachfully.

"Mr. Dene became convinced that an effort would be made to kidnap and
hold him to ransom, the price being the plans of the _Destroyer_.
Department Z. also became convinced of this, but at a later date. As a
precaution John Dene sent to England by another ship his twin brother,
known as James Grant. When everything was ready the two changed
places; that accounted for the strangeness of manner that Miss West
noticed with Mr. Dene a few days before his disappearance."

Malcolm Sage then went on to explain the method by which the false John
Dene had been kidnapped, and of Department Z.'s discovery with relation
to Mr. Montagu Naylor.

"But all that time what happened to the _Destroyer_?"

"The _Destroyer_ was responsible for the extraordinary increase in the
mortality among U-boats."

Mr. Llewellyn John jumped from his chair as if h