starting as he swung himself aboard. "So long, Tommy." The
train slid out of the station.

Tommy drew a deep breath. The man Boris was coming along the
platform towards him. Tommy allowed him to pass and then took up
the chase once more.

From Waterloo Boris took the tube as far as Piccadilly Circus.
Then he walked up Shaftesbury Avenue, finally turning off into
the maze of mean streets round Soho. Tommy followed him at a
judicious distance.

They reached at length a small dilapidated square. The houses
there had a sinister air in the midst of their dirt and decay.
Boris looked round, and Tommy drew back into the shelter of a
friendly porch. The place was almost deserted. It was a
cul-de-sac, and consequently no traffic passed that way. The
stealthy way the other had looked round stimulated Tommy's
imagination. From the shelter of the doorway he watched him go
up the steps of a particularly evil-looking house and rap
sharply, with a peculiar rhythm, on the door. It was opened
promptly, he said a word or two to the doorkeeper, then passed
inside. The door was shut to again.

It was at this juncture that Tommy lost his head. What he ought
to have done, what any sane man would have done, was to remain
patiently where he was and wait for his man to come out again.
What he did do was entirely foreign to the sober common sense
which was, as a rule, his leading characteristic. Something, as
he expressed it, seemed to snap in his brain. Without a moment's