After two minutes I had to lower the glasses, mesmerized. The agoraphobia still played in my senses, a hovering dread of exposure that I couldn't quite keep away as I stood here in the middle of the empty earth beneath the empty sky, a goose-flesh feeling of vulnerability: I was a creature without shelter, without a hiding-place, caught in a trap where the vastness of freedom itself imprisoned me.

I prefer the more natural haunts of my kind, the sooty warrens of the city streets, to this cosmic waste where the grains of sand are unimaginably many.

I turned twice more, full-circle.

At least there would be nomore effort needed,now that this point was reached. The reckoning had been wrong, that was all. Somewhere between the Philips tower and the zeros lining up on the computer there had been a mistake made in the figures. The margin of error,mon ami, is even larger than we'd thought.

There was no point in organizing a day's march: by the law of averages I would be as likely to move away from the wreck of the freighter as towards it. I had a compass but I didn't know the bearing. If I set off at random the odds against success were precisely three hundred and sixty to one.

Onset of lassitude, euphoria almost. Pain coming back, normal reaction, nothing important to do, can concentrate on the discomfort, crouched on the sand with my back to the heat and the light, here endeth the mission, you can't win them all. A vague sense of wonder that the sun was perfectly silent, sending this degree of heat over so much distance, you'd expect to hear a roaring, however faint, here where silence could be broken by a grain of sand hitting the side of a box.

My shadow humped before me, an insubstantial Buddha.

Try again I've tried then bloody well try again.

Lurching about, it's the sand, you can't ever get your balance. The red ring flaring at the edge of the field and the dunes flowing through, full-circle. Negative. Take a rest.

A kind of sleep, timeless and with no dream-element recalled, teeming images but so disconnected as to have no significance, then on my feet again and wandering about feeling stronger physically but not really determined about anything, the organism taking care of itself, getting the wind up because the box down there wasn't very big, forty-eight hours plus reserves and that's our lot.

Kept bumping my forehead against the eyepieces, sweat running down, awareness of sand in the boots and a thirst beginning, a certain amount of cerebration continuing: the parallax factor critically important because a near dune could block medium-field gaps, be an interesting thing to work out given a man of certain height standing upon a dune of a certain height and given a million dunes, the nearest of them concealing the gaps between those more distant, what proportion of the terrain can he actually observe, and what proportion is hidden from him?

To hell with academic problems: concentrate on the one thing that could just conceivably drag the mission back onits feet and yes, you snivelling little perisher, save our skin.

Parallax.

By lateral movement the observer exposes to view the gaps between distant dunes hitherto concealed by those in the foreground. By bodily rotation he increases this extension of view a hundredfold. Put it like that and it looks fair enough but the wreck isn't necessarily visible in one of the gaps, it can be lying on its belly full-square behind the highest dune of them all and you can practise your lateral movement and bodily rotation till the heat knocks you flat on your face.

The red ring flaring, the sand flowing through. The shadows changing as I turned from the sun through the south to the west. The sun hanging there in its roaring silence and pouring the sky ablaze across the eastern wastes of the earth until its tide lapped about me, burning.

They are there, the gaps you couldn't see before: you're looking at them now but can you tell which they are? You expect to find any difference between one thing and another in this region of the damned where the sun and the wind have driven away identity?

Turn. Keep turning.

Of course this wasn't the only dune in the Sahara and I got off it and tried another one because a kind of madness was setting in and although I knew about it I decided to ignore it because the organism had taken over a long time ago but it was going to be hard work: it was saying if we don't find the wreck and finish this job they won't ever pull us out and we'll die here so we're going to climb every dune in the desert till we see it, come on.

Climbed one of them twice, found my own tracks still there, getting rather dodgy, four times down there for a drink of water, not very slaking because it was warm.

The sands flowing like opaque flood-water through the vision-field, the gaps dipping like the lines on an electrocardiograph.

Turn. Keep turning.

Stop.

21°.

Now go down, go down and drink. And open up.

Tango.

Tango receiving.

I want to confirm that I am in fact in the target area.

You've seen the plane?

No. But I've sighted a rock. It should be the shale outcrop. According to the RAF people there's no other rock visible within seven miles of the objective and even on dead-reckoning Chirac couldn't have dropped me so wide.

He considered.

I would agree. How far away are you?

It's difficult to tell because the air's so clear. I'd say about two miles: it looks like one but I've doubled it.

What bearing is it?

Twenty-one degrees.

He was looking at the photograph and its annotations.

Then you should find the aeroplane almost directly in your path when you head for the outcrop. Its bearing from there is two hundred degrees.

I'll make my heading twenty. Change frequency?

Yes, to 7 MHz. Please repeat.

I repeated and asked for twin-synchro and we ended.

Then I did what I knew I would do: I went to the top of the dune and put up the Zeiss and looked again at the distant tip of rock. My life had depended on sighting this single landmark, and I wanted to be sure I hadn't dreamed up a mirage.

Their mass had been thrust upwards from the earth's crust to leave them standing reared and angular against the sky, their strata sloping at twenty or so degrees from the horizontal and their base littered with brittle fragments that had broken off. In several places a whole shoulder of rock had foundered, making an angled arch and giving shade, and under one of these I made my camp.

The flooring was the canopy of the supply 'chute and the roof was provided by my own, propped and draped with the help of the telescopic tubing that was part of the survival gear.

Lizards had run from the area of shade, skittering so fast across the sand that they seemed to float on its surface. I watched them, encouraged by the evidence of life in this region where I'd thought that nothing could hope to live.

For an hour I slept, in the heat of the noon. The distance had been nearer two miles than one and I'd had to make two trips, each time bringing a parachute and half the gear and provisions: four hours' work including rests in the shade of the rocks before I set up camp. Earlier, even when it had been cooler, this degree of effort would have been beyond me: it had been the sight of the tip of rock, the knowledge that it was there, that had given me the strength.

At 12.34 hours I made a signal.

He had to be told, before I decided what kind of effort was needed. Effort used up water and it used it up very fast. He had to be told, although there wasn't much he could do about it. The first thing was to get him to believe it.