have to, we have
to. But please rush it along, will you?"

"I'll do my best," promised the young officer. "Meanwhile, you had
better let me have your address--I mean the name of the hotel where you
will be staying--and I'll send you word as soon as I get it myself. I
had better tell you, though, that you will not be allowed to take any
pictures--moving or other kind--until you have received permission."

"We'll obey that ruling," Blake promised. He had hoped to get some views
of ruins caused by a Zeppelin. However, there was no hope of that.

On the recommendation of the young officer they took rooms in London at
a hotel in a vicinity to enable them to visit the War Department
easily. And then, having spent some time in these formalities and being
again assured that they would be notified when they were wanted, either
to be given permission to go to France or to testify against the two
suspects, the moving picture boys went to their hotel.

It was not the first time they had been in a foreign country, though
never before had they visited London, and they were much interested in
everything they saw, especially everything which pertained to the war.
And evidences of the war were on every side: injured and uninjured
soldiers; poster appeals for enlistments, for the saving of food or
money to win the war; and many other signs and mute testimonies of the
great conflict.

The boys found their hotel a modest but satisfactory one, and soon got
in the way of living there, planning to stay at least a week. They
learned that their food would be limited in accordance with war
regulations, but they had expected this.

There was something else, though, which they did not expect, and which
at first struck them as being decidedly unpleasant. It was the second
day of their stay in London that, as they were coming back to their
hotel from a visit to a moving picture show, Joe remarked:

"Say, fellows, do you notice that man in a gray suit and a black slouch
hat across the street?"

"I see him," admitted Blake.

"Have you seen him before?" Joe asked.

"Yes, I have," said Blake. "He was in the movies with us, and I saw him
when we left the hotel."

"So did I," went on Joe. "And doesn't it strike you as being peculiar?"

"In what way?" asked Charles.

"I mean he seems to be following us."

"What in the world for?" asked the assistant.

"Well," went on Joe slowly, "I rather think we're under suspicion.
That's the way it s