The three horsemen had been riding abreast, but at sight of the cart they moved into single file. The first was a German officer; then came the Serbian prisoner with the Bulgarian trooper holding the rope behind. The German officer reined up, and asked Marco a question. The boy shook his head, and the German turned impatiently to the prisoner, ordering him to repeat the question. At this moment Burton, revolver in hand, slipped from behind the cart on the side of the declivity, while the old man with some difficulty squeezed himself between the wheel and the high bank on the other side. A gleam in the eyes of the prisoner apprised the German that something was happening behind him, and he was in the act of turning when his arm was seized and he saw himself confronted by a determined-looking young airman, levelling a revolver within a few inches of his head. One arm was held as in a vice, the other hand was engaged with the rein; it was impossible to draw his own revolver. He called to the trooper to shoot, but that warrior was otherwise engaged. "Dismount, sir," said Burton, quietly. "You are my prisoner." [Illustration: "DISMOUNT, SIR."] And seeing that there was no help for it, the German made haste to obey. Meanwhile on the other side old Marco had performed his allotted part. The trooper, catching sight of Burton before the German, was for a moment too much surprised to be capable of action; but then, dropping the rope he held, he was about to spur forward to his superior’s assistance, when the old Serb, who had crept round while the man’s attention was occupied, suddenly hurled himself upon him. The old man was beset by no scruples. A Bulgar was always a Bulgar. A shot would raise an alarm; cold steel was silent. All the strength of his sinewy arm, all the heat of age-long national hatred, went into the knife-thrust that hurled the trooper from his saddle, over the edge of the track, and down the sharp-edged rocks of the slope beyond. Within less than a minute the ambush had succeeded without any sound or commotion that could have been heard by the enemy in the tower nearly two miles away, and out of their sight. IV "Milosh Nikovich, this is a good day, old friend," said old Marco, as he released the prisoner. "A good day indeed, Marco Kralevich. But I am amazed. Who is he that dealt with the German?" "Hand me that rope, if you please," came from Burton in French. "Clasp your hands behind, sir," he added to the German, in English. "You shpeak to me!" spluttered that irate officer. "Know you zat I am an officer, a captain of ze 59th Brandenburger Regiment? It is not fit zat I haf my hands bounden." "You must allow me to judge of that, sir," remarked Burton, with a quiet smile. "No, I protest. I refuse; it is insolence. You captivate me, zat is true; you seize me ven I look ze ozer vay; zat is not vat you call shport. But I gif you my parole----" "I can’t accept it, sir."