gray automobile had occupied the center of the station yard at
Waterloo when he took a taxi from the rank.

Admittedly he was in a nervous and excited state. It could hardly be
otherwise after the strain of that astounding conversation with
Forbes, and there was no prospect of the tension being relaxed until
the close of the interview with the detectives, which he now regarded
as the worse ordeal of the two.

But this subconscious neurasthenia in no wise affected the reflex
action of his ordinary faculties. When, on leaving the square, and
while his cab was rattling along an aristocratic thoroughfare leading
to Knightsbridge, he peered through a tiny observation window in the
back of the vehicle, and ascertained that the gray car was stealing
along quietly about a hundred yards in the rear, he began to believe
that its presence both at Waterloo and outside Mr. Forbes's residence
could not be wholly accidental. When he had watched its persistent
treading on his heels along Piccadilly its intent became almost
unmistakable.

The route to Innesmore Mansions traversed some of London's main
arteries, but, despite the rush of traffic due to the first flight of
homewardbound playgoers, the gray car kept steadily on his track.
Amused at first, be became angry because of a notion which grew out of
the wonderment of finding himself the object of this persistent
espionage.

To make sure, and at the same time discover the sort of person who was
spying on him, he adopted a ruse. Leaning out, when about to cross
Oxford Street into Tottenham Court Road, he said to his driver: "Turn