My rubber-soled sandals heel-and-toed it along the limestone rock without the slightest whisper of sound. No one could have heard me coming and, after I was clear of the faint luminescence of the cave-mouth, no one could have seen me coming. My torch was off. If there was anyone inside that mine I’d meet them soon enough without letting them know I was on the way. In the dark all men are equal. With that knife in my hand, I was slightly more than equal.
There was plenty of room between the wall and the railway track in the middle to make it unnecessary for me to walk on the sleepers. I couldn’t risk a sudden variation of length between a couple of ties. It was simple enough to guide myself by brushing the back of the fingers of my right hand against the tunnel wall from time to time. I took care that the haft of the knife did not strike solid rock.
Inside a minute, the tunnel wall fell away sharply to the right. I had reached the first hollowed-out cavern. I went straight across it to the tunnel opening directly opposite, guiding myself by touching the side of my left foot against the sleepers. It took me five minutes to cross the 70 yards’ width of that cave. Nobody called out, nobody switched on a light, nobody jumped me. I was all alone. Or I was being left alone, which wasn’t the same thing at all.
Thirty seconds after leaving the first cavern I’d reached the next one. This was the one where the professor had said the first archaeological discoveries had been made, the cavern with the two shored-up entrances to the left, the railway going straight ahead and, to the right, the tunnel where we’d found Hewell and his crew working. I’d no interest in the tunnel where we’d found Hewell working. The professor had given me to understand that that was the source of the explosions that had wakened me the previous afternoon, but all the amount of loose rock I’d seen lying there could have been brought down by a couple of good-sized fire-crackers. I followed the railway .across the chamber straight into the opposite tunnel.
This led to a third chamber, and then a fourth. Neither of those had any exits to the north, into the side of the mountain, as I found by walking round a complete semi-circle to my right before regaining the railway track again: I completed the circle in both chambers and found two openings to the south in each. But I went straight on. After that there were no more caverns, just the tunnel that went on and on.
And on. I thought I would never come to the end of it. There had been no archaeological excavations made here, it was just a plain and straightforward tunnel quite unconcerned with what lay on either side of it. It was a tunnel that was going someplace. I was having to walk on the ties now, the diameter had narrowed to half of what it had been at first, and I noticed that the gradient was slightly upward all the time. I noticed, too, that the air in the tunnel, and this at least a mile and a half after I’d left the mine entrance, was still fresh, and I guess that that explained the upward slant of the tunnel-it was being kept deliberately near the rising slope of the mountain-side to facilitate the driving of vertical ventilation shafts. I must have been at least halfway across to the western side of the island by then and it wasn’t very hard to guess that it wouldn’t be long before the tunnel floor levelled out and started to descend.
It wasn’t. The stretch of level floor, when I came to it, didn’t extend more than a hundred yards, and then it began to dip. Just as the descent began my right hand failed to find the tunnel wall. I risked a quick snap of the torch and saw a thirty-foot deep cavern to my right, half full of rock and debris. For one moment I thought this must be the scene of yesterday’s blasting, but a second look put that thought out of my mind. There were a couple of hundred tons of loose rock lying there, far too much for one day’s work, and besides, there was no percentage in driving suddenly north, into the heart of the mountain. This was just a storage dump, one probably excavated some time ago to provide a convenient deposit for the rock blasted from the tunnel proper, when the need arose to do that quickly.
Less than three hundred yards further on I found the end of the tunnel. I rubbed my forehead, which had been the part of me that had done the finding, then switched on the tiny pencil-beam of light. There were two small boxes lying o» the floor, both nearly empty, but still holding a few charges of blasting powder, detonators and fuses: this, beyond doubt, was the scene of yesterday’s blasting. I played the torch beam over the end of the tunnel and that was all it was, just the end of a tunnel, a seven-foot high by four-foot wide solid face of rock. And then I saw that it wasn’t all solid, not quite. Just below eye-level a roughly circular rock about a foot in diameter appeared to have been jammed into a hole in the wall. I eased out this lump of limestone and peered into the hole behind. It was maybe four feet long, tapering inwards to perhaps two inches and at the far end I could see something faintly twinkling, red and green and white. A star. I put the rock back in position and left.
It took me half an hour to get back to the first of the four caverns. I investigated the two openings leading off to the south, but they led only to two further caverns, neither of them with exits. I headed back along the railway till I came to the third of the caverns from the entrance, examined the two openings in this one and achieved nothing apart from getting myself lost in a maze for almost half an hour. And then I came to the second cavern.
Of the two tunnels leading off to the north, I passed up the one where Hewell had been working. I’d find nothing there. I found nothing in the neighbouring one either. And, of course, there would be nothing behind the timber baulks holding up the entrances to the two collapsed tunnels to the south. I made for the exit leading to the outer cavern when the thought occurred to me that the only reason I had for believing that those baulks of timber supported the entrances to a couple of caved-in tunnels was that Professor Wither-spoon himself had told me they did and, apart from the fact that he knew nothing about archaeology, the only certain fact that I had so far established about the professor was that he was a fluent liar.
But he hadn’t been lying about the first of these two tunnels. The heavy vertical three-by-six timbers that blocked the entrance were jammed immovably in place and when I pressed my torch against a half-inch gap between two of the timbers and switched it on I could clearly see the solid mass of stone and rubble that completely blocked the passage behind, all the way from the floor to the collapsed roof, Maybe I’d been doing the professor an injustice.
And then again maybe I hadn’t. Two of the timber baulks guarding the entrance to the second barricaded tunnel were loose.
No pickpocket ever lifted a wallet with half the delicate care and soundless stealth that I used to lift one of these baulks out of position and lean it against its neighbour. A brief pressure on the torch button showed no signs of a roof collapse anywhere, just a dingy grey smooth-floored tunnel stretching and dwindling away into the darkness. I lifted a second batten out of place and squeezed through the gap into the tunnel beyond.
It was then that I discovered that I couldn’t replace the battens from the inside. One, yes, but even then only roughly in place, but it was impossible to manoeuvre the other through the six-inch gap that was left. There was nothing I could do about it. I left it as it was and went down the tunnel.
Thirty yards and the tunnel turned abruptly to the left. I was still guiding myself as I had done earlier on, by brushing the back of my right hand against the wall, and suddenly the wall fell away to the right. I reached in cautiously and touched something cold and metallic. A key, hanging on a hook. I reached beyond it and traced out the outlines of a low narrow wooden door hinged on a heavy vertical post of timber. I took down the key, located the keyhole, softly turned the lock and opened the door a fraction of an inch at a time. My nostrils twitched to the pungent combined smells of oil and sulphuric acid. I eased the door another two inches. The hinges creaked in sepulchral protest, I had the sudden vision of a gibbet and a swaying corpse turning in the night wind and the corpse was myself, then I snapped abruptly to my senses, realised that the time for pussyfooting was over, passed quickly round the door and closed it behind me as I switched on the torch.