'Hulloa, Hurree! Can you hear me?' Mr Holmes's distant voice slowly filtered into my scrambled mind. I shook my head to clear it.

'I am here, Mr Holmes!' I yelled back.

'Are you all right?'

I took stock of my condition and situation. 'I think so, Sir. There are no bones broken, anyway.'

'Excellent. Where exactly are you?'

'I seem to be at the bottom of an awful abyss, Sir. I am of the opinion that the entrance should be somewhere in the middle of the wall opposite the temple door.'

'Good man. Hang on for a minute. I'll get a light down there soon.'

A few moments later a welcome glow of light appeared in the darkness above me. Gradually, as the light descended and became brighter, I was able to discern the comfortably familiar outline of Sherlock Holmes' tall figure, holding the dark lantern and walking down a long stone staircase – which must have been the one I had tumbled down. Behind him the two Lamas followed.

'You are to be congratulated, Hurree,' said Holmes cheerfully, coming up to me. 'The honour of discovering the secret of the mandala is yours.'

'Is this all, Mr Holmes?' said I, disappointed. 'All that mystery and noise and fuss, just to conceal a passage way?'

'Patience. We shall know when we get to the end of it.' He pointed the lantern in the direction opposite to the staircase. 'See, it does not stop here but continues much further.'

The Lama Yonten and the Grand Lama made solicitous enquiries as to my state of health subsequent to my sudden descent, and gave loud thanks to the 'Three Jewels', the Buddhist Trinity, for my deliverance.

We proceeded down the passage cautiously, with Mr Holmes in the lead holding the lantern, and the rest of us following closely behind him. Though the passage was very long it was surprisingly straight and true, without even the slightest bend, dip or rise during its entire length. The walls were constructed to an exactness that would certainly tax a modern engineer. As we proceeded, the light from the lantern shimmered off the surface of the walls. I reached out to touch it and was surprised to discover how smooth it was – smoother than marble, even glass. There were no seams or joints, no interruptions of any kind in the unnatural evenness of the surface. It had clearly been made by a people with very advanced technical knowledge. I mentally began to review all the bits of information I had now acquired about my Tethyian civilisation, and tried to classify them in some systematic order.

Suddenly Mr Holmes paused and signalled us to halt. He then directed the beam of the lantern straight to the floor, which like the temple, was covered with a thin carpet of powdery snow. We were probably arriving at a place where drifts of snow could somehow enter this subterranean corridor.

'What do you think of that?' he asked, indicating a number of footprints clearly impressed on the soft snow.

'Obviously someone has anticipated us,' said I, worried.

'More than one, I'm afraid. There are three distinct sets of impressions. I first observed them just a littie way ago. One of them is obviously a cripple. Notice how the impression of the right foot is quite askew, and also blurred because he dragged that foot.'

'Moriarty!' I exclaimed in horror.

'Yes. As I expected, the Dark One has got here before us. One of his companions led the way, he came next, and the third followed as rearguard. There can be no question as to the superimposition of the footmarks.'

'Do you think the Amban is with him?' asked the Lama Yonten.

'Probably not. The two other impressions are from the same kind of footwear – cheap, cloth-soled Chinese boots, I would think; the kind that can be worn on either foot. I noticed the Chinese soldiers wearing them.'

I was not at all happy about our proceeding with this particularly dangerous venture, especially when highly unscrupulous bounders, fully prepared to commit violences against our persons, awaited us at the end of it.

'Hadn't we better… ' I began to make a suggestion.

'We are doing so,' Holmes interrupted me rather brusquely. He extracted a revolver from within the folds of his robe and cocked it. 'It would be well if we were to proceed with all due caution. Hurree? You are armed?'

'Yes, Sir,' I said resignedly, pulling out the ludicrous weapon from my belt, and began to go through the motions of preparing it for the coming fray.

'You Hurree, will bring up the rear. If anything should happen to me, you will at once escort His Holiness and the Lama Yonten out of this place. Now close the shield of the lantern. We will have to manage in the dark.'

We moved very carefully along the passage, which now gradually, almost imperceptibly, became wider, and strangely less dark, or so I imagined. As we went forward the phenomena became more apparent. Unwilling to trust my own visual senses I tentatively imparted to Mr Holmes my assessment of the luminary intensification. He had noticed it too.

'You are right, Hurree, and it is getting progressively lighter further up the passageway. We must double our precautions. The light will make us more visible, and more vulnerable.'

For another half an hour we advanced stealthily. By this time the passage had so enlarged that it was now the dimensions of a large cathedral. It was also now quite simple to locate the source of our illumination. Hundreds of feet above us hung a massive roof of clear glacial ice, via which a remote daylight filtered through to provide a pale unearthly luminescence in the cavern below.

As we sidled by the left wall of the gigantic passage way, glancing nervously up at this tremendous anomaly of nature, the thought of those millions of tons of unstable ice poised menacingly above our heads did nothing to reassure me about the wisdom of our enterprise. A little way ahead there was a narrow opening in the wall – probably a cleft in the rock, but with the regular lines of an entrance of some kind. Maybe it was the beginning of a branch passage, or the door to a chamber.

Sherlock Holmes stopped a little way before the opening and, getting down on one knee, carefully inspected the white floor. CI don't like it. The alignments of the footmarks change here. They do not all point forward as before, but instead point toward each other in a rough circle. Obviously they gathered around here to confer.'

Meanwhile I had proceeded to the side entrance to have a look inside. I was just stepping into the opening when Mr Holmes shouted a warning. 'Stop, Hurree It is a trap!'

Instinctively I drew back, which was most fortunate, for two shots rang out, the bullets whizzing perilously close past me. I pressed my back hard against the wall and tried to control my breathing and the rhythm of my heart, which were now totally at sixes and sevens. Pressing himself against the wall, Mr Holmes sidled up besides me. 'Moriarty and his men conferred here to prepare a trap for us,' he whispered. 'But in baiting a mouse-trap with cheese, it is well to remember to leave room for the mouse. The entrance was rather too obvious. The footmarks also provided a useful confirmation.'

'But what can we do now, Mr Holmes? I asked. We can only proceed at unequivocal peril to life and limb.'

'Let us not succumb to such morbid anticipations before having exhausted our own resources.' Holmes said sternly. 'First of all we must establish the exact circumstances of our adversaries. Hurree, if crouching very low, you could quickly peep around the corner and fire a few shots in their general direction, it may afford me the opportunity to make a quick reconnaissance. Are you ready? Now!'

I fired three rapid shots around the corner and whipped back to safety, just before a volley of rifle-fire crashed past me and echoed through the many miles of empty caverns. Mr Holmes had managed to duck back safely also, and he now stood with his back pressed to the wall and his eyes filled with frustration.