'Now pile all the stones into the hole again,' said our hero, superintending the job. 'As soon as the place is cool enough those gentlemen will return, and we shall want another barrier. Quick with it. Those bales are nearly burned out now, and a starving mob don't wait for much. A little heat under foot will be nothing if they can only appease their hunger. Poor beggars! I'm sorry for them. But then, what would you have? This is a case of saving one's self.'

Less than ten minutes later a man descended the stairway, and peeped over the barrier. His shout of amazement brought a crew of cut-throats racing after him; then such yells of anger and disappointment arose as they discovered the chamber empty that the men who had joined the Professor that morning were terrified. There was a determined rush for the gap, now more than half-filled, a rush which Chu-Li and two of his comrades checked instantly. Indeed, the enemy bolted at once from the chamber.

'Pick off every man you can see,' said David, staring over the barrier of stones. 'Don't let any one enter the room. This is a much easier place to defend than the other. Ah! They're moving. What new game are they up to?'

The whole party listened to the shouts of the enemy, and were amazed to see them bolting from the covered way. Chu-Li slid through the gap like an eel, and ran to the door. Then he waved his arms frantically, and rushed back to his comrades.

'They are bolting, Excellencies!' he shouted. 'They are completely gone. I heard firing above, and caught sight of several soldiers. I believe a relief party has arrived.'

Five minutes later there was no doubt of the fact, for when the Professor and his staff clambered up the stairway there was a troop of Chinese cavalry drawn up. Not a troop of men armed with ancient bows and arrows, but soldiers that China is training now-a-days, armed with modern weapons, equipped to the last button, able to manœuvre with the best. A dapper little officer spurred forward, saluted in German style, and at once addressed the Professor in the purest English.

'I have the honour to speak with the Professor who undertakes excavations, is it not so?' he demanded. 'Then let me explain. Five thousand troops were sent into these parts by His Excellency, Twang Chun, to arrest the movement of people from the plague-stricken country, and to break up the gangs of half-starved and dangerous men prowling about. I heard yesterday that a mob had passed west with the intention of evading me. I rode this way before sunrise, and met your messenger. I have the pleasure to find that I am in time.'

Near at hand the remainder of the gang which had attacked the party at the ruins were huddled together in a forlorn group, surrounded by soldiers, while the plain was dotted with the bodies of those who had shown fight, and had fallen. It was clear, in fact, that the danger had passed altogether.

'I give you the thanks of every one here,' said the Professor, gripping the little officer's hand. 'You came in time and have done us a great service. Step down below and see what happened.'

'Truly, you put up a fine defence,' declared the commander of the troop of horsemen, as he inspected the chamber below. 'That gap undoubtedly saved the situation, and not my arrival. Still, those desperate men would have fought on till you or they were conquered. I am vastly interested in this work which you have undertaken. How strange that you should have hit upon another part from which all debris had been cleared?'