There was no one in the block at the
moment but herself and Mr. Hoff. If Fleck's men had been watching his
movements, the old man certainly seemed to have eluded them.

What should she do? Vividly there flashed into her mind her chief's
parting words.

"Watch everything," he had charged her. "Remember everything, report
everything. No detail is too unimportant. If you see one of the Hoffs
leave the house, don't merely report to me that the old man or the young
man left the house about three o'clock. That won't do at all. I want to
know the exact time. Was it six minutes after three or eleven minutes
after three? I must know what direction he went, if he was alone, how
long he was absent, where he went, what he did, to whom he talked. Here
in my office I take your reports, Carter's reports, a dozen other
reports, and study them together. Things that in themselves seem
trifling, unimportant, of no value, coupled with other seemingly
unimportant trifles sometimes develop most important evidence."

To prove his point he had told her of the seemingly innocent wireless
message that an operator, listening in, had picked up, at a time when
Germans were still permitted to use the wireless station on Long Island
for commercial messages to the Fatherland. On the face of it, it was the
mere announcement of the death of a relative with a few details. But a
little later the same operator caught the same message coming from
another part of the country, with the details slightly different, and
still later another message of the same purport. Evidently, by comparing
the messages, the United States authorities had been able to work out
a code.

Remembering this, Jane decided that it was her particular duty just now
to follow the old German and note everything he did. For several blocks
she trailed along behind him, without arousing any suspicion on his part
that he was being followed. He stopped once to light a cigarette, the
girl behind him diverting suspicion by hastily turning to a shop window.
Again he stopped, this time before the display of viands in the window
of a delicatessen store. Thoughtfully Jane noted the number, observing,
too, that the name of the proprietor above the door was obviously
Teutonic. She was half-expecting to see her quarry turn in here, but he
walked on to the middle of the next block, where he entered a
stationery store.

Hesitating but a second, to decide on a course of action, she followed
him bold