strength in his body into a mighty heave. The next second he was lying on his back. The greater part of the wall had collapsed. He was curious enough to examine the work he had demolished. It had evidently been done by amateurs, and the whitewash which had been thickly applied to the passage was explained.
A current of fresh air came to meet him as he stepped gingerly across the debris. A flight of six stone steps led down to a small room containing a sink and a water supply, two camp beds which had evidently been part of the ambulance equipment and which the new owners had not thought necessary to remove, and a broken chair. The room was still littered with the paraphernalia of first-aid. He found odd ends of bandages, empty medicine bottles and a broken glass measure on the shelf above the sink.
What interested him more was a door which he had not dared to hope he would find. It was bolted on his side, and when he had slid this back he discovered to his relief that it was not locked. He opened it carefully, first extinguishing his light. Beyond the door was darkness and he snapped back the light again. The room led to another, likewise empty. There were a number of shelves, a few old wine-bins, a score of empty bottles, but nothing else. At the far corner was yet another door, also bolted on the inside. Evidently van Heerden did not intend this part of the vault to be used.
He looked at the lock and found it was broken. He must be approaching the main workroom in this new factory, and it was necessary to proceed with caution. He took out his revolver, spun the cylinder and thrust it under his waistcoat, the butt ready to his hand. The drawing of the bolts was a long business. He could not afford to risk detection at this hour, and could only move them by a fraction of an inch at a time. Presently his work was done and he pulled the door cautiously.
Instantly there appeared between door and jamb a bright green line of light. He dare not move it any farther, for he heard now the shuffle of feet, and occasionally the sound of hollow voices, muffled and indistinguishable. In that light the opening of the door would be seen, perhaps
