was that fact to be reconciled with what had befallen him? Probably Mr.
Wernberg had been injured accidentally as Sergeant Riley had explained.
At all events Lena was hurrying along through the crowd and Bob's task
was to follow her. His father was watching Heinrich and it would never do
for Bob to let his quarry escape him.

Lena followed the main street for several squares. The crowd was still
thick, but Bob kept his eyes on her. Presently she turned down a side
street, where it was easier to follow her and Bob heaved a sigh of
relief. He was sure he could keep track of her now, and his mind was
easier. They passed fewer people all the time, and now the only
illuminations were the street lamps and an occasional arclight.

Bob dropped further behind. His one wish was to avert suspicion on Lena's
part, and the sight of a tough-looking man with heavy black whiskers, old
clothes, and a dilapidated slouch hat dogging her footsteps might well
have made her uneasy.

Every hundred feet or so Lena cast a quick glance over her shoulder. Bob
did not walk on the stone pavement, but skulked along in the shadow of
the hedges and fences except when a passerby came along. Consequently
whenever Lena looked behind her he stood still. It was exciting work.

A half-mile or so down the street Lena stopped. She stood under one of
the street lamps, and after a sharp glance in all directions, stealthily
drew a piece of paper out of the bag she carried. She was plainly
nervous, and Bob watched her intently. She was about to read the note
that the fake detective had handed to her.

It took Bob only a second to make up his mind. The occasion called for