delusion, was sometimes tantamount to refusing aid to a man in
deadly peril.

"You are naturally anxious for the particulars," Sir Charles
presently resumed. "They bear, I regret to say, a close
resemblance to the symptoms of a well-known form of
hallucination. In short, with one exception, they may practically
all be classed under the head of surveillance."

"Surveillance," said Paul Harley. "You mean that you are more or
less constantly followed?"

"I do."

"And what is your impression of this follower?"

"A very hazy one. To-night, as I came to your office, I have
every reason to believe that someone followed me in a taxicab."

"You came in a car?"

"I did."

"And a cab followed you the whole way?"

"Practically the whole way, except that as my chauffeur turned
into Chancery Lane, the cab stopped at the corner of Fleet
Street."

"Your idea is that your pursuer followed on foot from this