“The real clew,” he said at last, “rests with the gray car.  What did you make of that?”

“That, my bulky friend, will figure in my memory as a reproach for many a year.  When, if ever, I am tempted to preen myself on some peculiarly close piece of ratiocinative reasoning, I shall say:  ‘Little man, pigmy, remember the gray car.’”

“You think that some one had the impudence to follow us, watch us in Waterloo, and take up Theydon’s trail when we had revealed it?”

“A-ha.  It touched you, too, did it?”

“But why?”

“The some one in question wants to know that.”

“You mean they are anxious to find out what we are doing?”

“Exactly.”

Winter laughed cheerfully.

“Before long I shall begin to enjoy this hunt, Charles.  I like to find originality in a felon.  It varies the routine.  At any rate, it is something new that you and I should be shadowed by the very people we are in pursuit of—­ O, I was nearly forgetting.  Anything fresh in that telephone talk?”

“It seemed all right.”

“Seemed?”

“Well, it was too straightforward.  Theydon puzzles me.  I admit it frankly.  He also worries me.  But let me handle him in my own way.  Have no fear that he will use our material for newspaper purposes.  With regard to the Innesmore Mansions affair, Theydon will lie close as a fish.  Why?  No use asking you, of course.  You despise intuition.  When you die some one should begin your epitaph:  ’From information received.’  But I’ll stick to Theydon.  See if I don’t, even if I have to go up with him in one of Forbes’s airships.”

CHAPTER V

 A leap in the dark

With the morning Theydon brought a mature and impartial judgment to bear on his perplexities.  The average man, if asked to form an opinion on any difficult point, will probably arrive at a saner decision during the first pipe after breakfast than at any other given hour of the day.  Excellent physiological reasons account for this truism.  The sound mind in a sound body is then working under the most favorable conditions.

It is free from the strain of affairs.  The cold, clear morning light divests problems of the undue importance, or, it may be, the glamour of novelty, which they possessed overnight.  At any rate, Frank Theydon, clenching a pipe between his teeth, and gazing thoughtfully through an open window at the trees in Innesmore Gardens, reviewed yesterday’s happenings calmly and critically, and arrived at the settled conviction that his proper course was to visit Scotland Yard and make known to the authorities the one vital fact he had withheld from their ken thus far.

It was not for him to assess the significance of Mr. Forbes’s desire to remain in the background.  If the millionaire’s excuse, or explanation, of his failure to communicate at once with the Criminal Investigation Department was a sufficiently valid one, Scotland Yard would be satisfied and might agree to keep his name out of the inquiry.