“I don’t know,” replied Hal, answering Chester’s question.  “Something seems to have gone wrong with the engine.  Guess we had better go down.”

He tilted the elevating levers and the plane descended gradually and swiftly.

Under Hal’s firm hand it settled gently upon the ground and all immediately climbed out.  Stubbs drew a great breath of relief.

“I never expected to reach here alive,” he declared.

Ivan and Nikol also were plainly relieved.  They said nothing, but the expression upon both their faces spoke plainer than words.

Hal bent over the engine.  As he straightened up, Chester asked: 

“Anything serious?”

“Believe I can fix it within an hour,” replied Hal.  “I’ll have a try at it, anyhow.”

“Need any assistance?” asked Colonel Anderson.

Hal shook his head.

“Nothing you can do, I guess,” he replied.

“Then I am going to take a little prowl into these woods here,” said the colonel, indicating a small clump of trees that stood perhaps a quarter of a mile to the east.

“I’ll go along,” said Chester.  “I feel like stretching my legs a bit.”

The two walked away together.  Ivan and Nikol remained behind and watched Hal tinker with the engine.

Chester and the colonel prowled about among the trees for the better part of half an hour and then turned to make their way back to the machine.  As they walked along, Chester suddenly caught Colonel Anderson by the arm, stopping him in his stride.

“Sh-h-h,” muttered the lad and listened intently.

“What’s the matter?” demanded Colonel Anderson, in a low voice.

“Thought I heard voices,” replied Chester.  “Listen.”

Both became silent; and directly they caught the sound of a low voice off to the right.  Then there came a second and a third voice.

“Don’t see what they can be doing here, whoever they are,” declared Chester in a whisper.  “We’ll see if we can get a look at them.”

He led the way softly in the direction from which the voices had come.  The voices became louder; and directly, parting two large bushes, Chester made out the forms of three figures not ten yards away.

He turned quickly to Colonel Anderson and laid a finger to his lips.  The colonel approached cautiously.

From the spot where the two stood it was possible to see the three men in front of them without danger of being seen themselves, for they were screened from sight by the large bushes.  One of the men was attired in what Chester took to be a Serbian uniform, but the others were in civilian attire.

“We’ll do a little eavesdropping,” whispered Chester.

Colonel Anderson nodded and they became silent.

“So you say that everything is ready for Bulgaria’s entrance into the war?” spoke the man with the uniform.

“Yes,” replied one of the others, a man of perhaps forty years of age, with a long flowing beard.