“And what are we to do in the meanwhile?” asked Blake.

“I fancy you’ll just have to stay here and—­what is it you say—­split kindling?”

“‘Saw wood,’ I guess you mean,” said Joe.  “Well, if we 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 strikes me!”

CHAPTER XIV

IN CUSTODY

Blake and Charlie nodded their heads as Joe gave voice to his suspicion.  Then, as they looked across once again at the man in the slouch hat, he seemed aware of their glances and slunk down an alley.