For a matter of ten minutes Thomson was busy with his pencil and the
code-book. When he had finished, he studied thoughtfully the message
which he had transcribed:--

Plans for attack on La Guir communicated. Attack foiled. Believe
Smith in London.

"Anything important, sir?" the young man at the typewriter asked.

Thomson nodded but made no immediate reply. He first of all
carefully destroyed the message which he had received, and the
transcription, and watched the fragments of paper burn into ashes.
Then he replaced the code-book in the safe, which he carefully
locked, and strolled towards the window. He stood for several minutes
looking out towards the Thames.

"The same thing has happened again at La Guir," he said at last.

"Any clue?"

"None. They say that he is in London now."

The two men looked at one another for a moment in grave silence.
Ambrose leaned back in his chair and frowned heavily.

"Through our lines, through Boulogne, across the Channel, through
Dover Station, out of Charing-Cross, through our own men and the best
that Scotland Yard could do for us. In London, eh?"

Thomson's face twitched convulsively. His teeth had come together