‘The next stage is the Valley of Humiliation,’ I answered.

‘So it would appear,’ she said gravely, and sat very quietly on the edge of Sir Walter’s chair with her small, cool hand upon his.

I had been picturing her in my recollection as very young and glimmering, a dancing, exquisite child.  But now I revised that picture.  The crystal freshness of morning was still there, but I saw how deep the waters were.  It was the clean fineness and strength of her that entranced me.  I didn’t even think of her as pretty, any more than a man thinks of the good looks of the friend he worships.

We waited, hardly speaking a word, till Macgillivray came.  The first sight of his face told his story.

‘Gone?’ asked Blenkiron sharply.  The man’s lethargic calm seemed to have wholly deserted him.

‘Gone,’ repeated the newcomer.  ’We have just tracked him down.  Oh, he managed it cleverly.  Never a sign of disturbance in any of his lairs.  His dinner ordered at Biggleswick and several people invited to stay with him for the weekend—­one a member of the Government.  Two meetings at which he was to speak arranged for next week.  Early this afternoon he flew over to France as a passenger in one of the new planes.  He had been mixed up with the Air Board people for months—­of course as another man with another face.  Miss Lamington discovered that just too late.  The bus went out of its course and came down in Normandy.  By this time our man’s in Paris or beyond it.’

Sir Walter took off his big tortoiseshell spectacles and laid them carefully on the table.

‘Roll up the map of Europe,’ he said.  ’This is our Austerlitz.  Mary, my dear, I am feeling very old.’

Macgillivray had the sharpened face of a bitterly disappointed man.  Blenkiron had got very red, and I could see that he was blaspheming violently under his breath.  Mary’s eyes were quiet and solemn.  She kept on patting Sir Walter’s hand.  The sense of some great impending disaster hung heavily on me, and to break the spell I asked for details.

‘Tell me just the extent of the damage,’ I asked.  ’Our neat plan for deceiving the Boche has failed.  That is bad.  A dangerous spy has got beyond our power.  That’s worse.  Tell me, is there still a worst?  What’s the limit of mischief he can do?’

Sir Walter had risen and joined Blenkiron on the hearthrug.  His brows were furrowed and his mouth hard as if he were suffering pain.

‘There is no limit,’ he said.  ’None that I can see, except the long-suffering of God.  You know the man as Ivery, and you knew him as that other whom you believed to have been shot one summer morning and decently buried.  You feared the second—­at least if you didn’t, I did—­most mortally.  You realized that we feared Ivery, and you knew enough about him to see his fiendish cleverness.  Well, you have the two men combined in one man.  Ivery was the best brain Macgillivray and I ever encountered, the most cunning and patient and long-sighted.  Combine him with the other, the chameleon who can blend himself with his environment, and has as many personalities as there are types and traits on the earth.  What kind of enemy is that to have to fight?’