For a few moments consternation and dismay paralysed their faculties. That the horsemen formed part of the patrol they had already seen was certain; no others could have safely passed the tower occupied by the enemy. Discovery and capture seemed inevitable. The fugitives might, indeed, clamber among the rocks and conceal themselves for a time; but the nature of the ground at this spot precluded the removal of the cart, and its tell-tale presence on the track unattended would put a short limit to their safety. At this critical moment the old Serb’s experience of half a century of mountain warfare came to his aid. "We must ambush the Bulgars," he said. "Look there!" He pointed to a spot a few yards in their rear, at the end of a narrow stretch of the track which had given him an anxious moment in leading the oxen. On one side the bank rose rugged and steep, on the other it fell away, not precipitously, but in a jagged slope which had threatened ruin to the cart if the wheel had chanced to slip over the edge of the track. Burton quickly seized the possibilities of the situation. "By Jove! It’s risky, but we’ll try it," he remarked to Enderby. The captain had already taken his revolver from its case. But old Marco had conceived a plan that would render Captain Enderby’s co-operation unnecessary. He explained it rapidly to Burton, and they proceeded to carry it out. The woman was told to conceal herself behind a thorn bush growing in a cleft in the bank. The cart was backed to the chosen spot, and young Marco, his eyes alight with excitement and eagerness, clambered up to the driver’s seat. A rug was thrown over Enderby and the machine-gun lying at his side, and the old man took up a position with Burton behind the cart, concealed by the pile of furniture from the eyes of any one approaching down the hill. The Serb had taken a rifle from beneath the baggage. "There are only three," he said. "I can shoot them one by one." "No, no!" cried Burton. "The shots would alarm their friends above. Besides, they’ll be more useful to us alive, as hostages, perhaps, even if we don’t get useful information out of them." "You are right," said the old man, "but it is a pity," and he reluctantly laid the rifle aside. They had reason to commend young Marco’s scouting, for only a few minutes after their preparations were completed, the horsemen were heard approaching the bend. The boy, whose eyes had been fixed on his grandfather, at a nod from him whipped up the oxen, and the cart lurched forward just as the horsemen came in sight. As if surprised by their appearance, Marco pulled up so that there was barely room for a horse to pass on the side where the bank shelved downwards. His grandfather and Burton were still hidden in the rear.