“All we wish to know, sir,” said Hal, “is whether Robard still is at the Austrian embassy.”

“He is,” was the reply, “and will be until some time to-morrow, when the ambassador will be given his passports.”

“Can I be of any assistance?” asked Colonel Fuesco, stepping forward.

“If you can, we shall call on you,” replied Hal.

“Good,” said the colonel, and, drawing out a card, he scribbled an address on it.  “You will find me there,” he said.  “I shall remain at my quarters in the hopes that I may be given a hand in the game.”

The lads shook hands with the general and walked to the door.

“Wait a moment, boys,” said Major Derevaux.  “I want a few words with the general, and then I shall be at liberty to go with you.”

“If it is all the same to you, Major Derevaux,” said the general, “I would prefer to postpone our conference until this evening.  I have several matters that require my immediate attention.”

Major Derevaux accepted this postponement graciously, and announced that he would accompany the boys at once.  As they would have passed out, the general’s orderly once more entered the room.

“The American ambassador is without, sir,” he said, “and demands an immediate interview with you.”

General Ferrari turned to Colonel Fuesco.

“You see what trouble you have brought down on my head,” he said, with a smile.  “I won’t bother to see the ambassador now,” he said to his orderly.  “I shall send these lads to greet him.”

In response to these words, Hal and Chester, accompanied by Major Derevaux and Colonel Fuesco, made their way from the room.  In the corridor they encountered the American ambassador and Uncle John.  The latter was walking back and forth nervously and muttering angrily to himself.

“Here we are, Uncle John,” said Chester.

Uncle John jumped as though he had been shot, for he had not perceived their approach.

“You young rascals,” he exclaimed, “so you have been released, eh?”

“Yes,” said Chester quickly, “we have been released providing we can really apprehend the man who is the spy.”

“What do you mean?” asked Uncle John anxiously.

Hal followed Chester’s lead, for he wished no obstacle to be put in their path.

“If we can catch the spy, we shall be permitted to go free,” he said,

“I see,” said Uncle John.  “But I can’t see that spy-catching is any of your business.”

“Well, we have promised to do the best we can,” said Chester.

“In that case, I have nothing to say,” said Uncle John.  “But remember we are due to sail for home to-morrow.”

“Oh, we can wait over for the next ship,” said Chester.

“Perhaps,” said Uncle John, with a twinkle in his eye.  “We shall see what your mothers have to say about that.”

Hal now bethought himself to introduce Uncle John to his friends.  This accomplished, the American ambassador announced that he would be moving, and took his departure.  The others Uncle John invited to have lunch with him in a nearby hotel.