The door slammed, a key grated harshly and the prisoners were left alone.

“Now what in the name of all that’s wonderful do you suppose this means?” asked Chester.  “Think they are going to leave us here to starve or perish of thirst?”

“No, I guess not,” was the reply.  “My opinion is that Robard is up to something funny, and that he has enticed the ambassador here on some pretext or another.”

“What do you think he is up to?” demanded Chester.

“If I knew I’d have told you a long while ago,” said Hal.  “Now, if we—­”

He paused as Chester held up a warning hand.  The latter moved toward the wall at the far end of the room as Hal eyed him curiously.  The lad placed his ear against the wall, and listened intently for a moment; then he motioned Hal and Uncle John to approach.

“The ambassador and Robard are in the next room,” he whispered.  “I can hear them talking.  Listen.”

Hal and Uncle John also laid their ears to the wall.

“But,” and the ambassador’s voice came faintly to them, “such a thing as you suggest is dishonorable.”

“What has that to do with it, sir?” came Robard’s reply.  “Our enemies would do the same thing had they the opportunity.  All’s fair in war, you know, sir.”

“Not that,” said the ambassador.  “You must remember that until I have crossed the frontier I am still the ambassador to Italy.  I am upon my honor to leave the country peaceably.”

“But no one would know you had a hand in the matter, sir.”

“That is not the point,” was the reply.

“But I have made all arrangements,” protested Robard.  “Everything is ready.  The chief of the Italian general staff is in Venice at this moment, and at noon will inspect the large stores of ammunition at the northern outskirts of the city.  A word from you and ammunition, chief of staff and all will be destroyed.”

“I will give no such word,” was the angry response.  “Besides,” and the ambassador considered a moment, “why do you wish a word from me in this matter?  It could have been done without my consent.”

“Well, sir, I—­we—­I,” stammered Robard, evidently at a loss for a convincing reply.

There came the sound of a blow, as though a hand had struck a table and the ambassador’s voice rose angrily.

“Robard,” he said sternly, “I can see through your plot.  You would have me stand sponsor for this crime, that you might disqualify me upon my return to Vienna.”

“I assure you, sir—­” began Robard.

“Enough,” replied the ambassador.  “I have not forgotten that you were ever my enemy—­at least until this war brought us closer together and put an end to all our disputes—­at least, so I believed.  Now I know better.”

“Sir—­” Robard began again.

“I have told you I would have no hand in it,” declared the ambassador.  “What is more, I forbid it!  Do you understand, I forbid it!”