Our first job, the removal of the hoped canvas hood, gave us some measure of the difficulty of the task that lay before us. The hood was secured by only seven bolts and nuts, but these had been in position for over four months now, were frozen solid and took over an hour to remove: each set had to be thawed out separately by blow-torch before the heavy wrenches could get the nuts to turn.

Then came the assembly of the wooden body. This was in fifteen prefabricated pieces, three each for the floor, sides, roof and front – the back was only a canvas screen. Each set of three pieces had to be brought out singly through the narrow hatchway before assembly, and it was the devil's own job, in that numbing cold and flickering semi-darkness, to locate and line up the bolt-holes in the wood with the matching holes in the connecting iron cross-pieces. It took us well over an hour to assemble and fit the floor section alone, and it was beginning to look as if we would be here until midnight when Corazzini had the idea – and a brilliant one it seemed at the time – of assembling the various sections in the comparative warmth and brightness of the cabin, sliding the complicated piece out vertically into the food and fuel tunnel, sawing a long narrow slit through the snow roof, which was no more than a foot thick in the middle, and hauling the sections up from below.

After this we made rapid progress. By five o'clock the entire body shell was completed and with the end in sight less than a couple of hours away, everyone worked more furiously than ever.

Most of them were unskilled, ham-handed and completely unused to any physical work at all, far less work of this cruel, exacting nature, but my opinion of them was rising all the time. Corazzini and Zagero especially, were tireless, and Theodore Mahler, the silent little Jew whose entire conversational range so far had been limited to 'Yes', "No', "Please' and 'Thank you', was indefatigable, completely selfless and uncomplaining, driving his slight body to lengths of which I would never have believed it capable. Even the Senator, the Rev. Smallwood and Solly Levin did what they could, as best they could, trying their best to hide their misery and their pain. By this time everyone, even Jackstraw and myself, was shaking almost uncontrollably with the cold so that our hands and elbows rat-tat-tatted like machine-guns against the wooden sides of the tractor: and our hands themselves, through constant contact with metal were in a shocking state, puffed and bleeding and blistered, the mittens continuously filled with lumps and slivers of ice that never melted.

We had just installed the four collapsible bunks and were fitting the stove-pipe through its circular hole in the roof when someone called me. I jumped down and all but knocked over Marie LeGarde.

"You shouldn't be out here," I scolded. "It's far too cold for you, Miss LeGarde."

"Don't be silly, Peter." I could never bring myself to call her 'Marie', though she had asked me to several times. "I have to get used to it, don't I? Would you come below for a moment or two, ptease?"

"Why? I'm busy."

"But not indispensable," she retorted. "I want you to have a look at Margaret."

"Margaret – oh, the stewardess. What does she want?"

"Nothing. It's I who want it. Why are you so hostile towards her?" she asked curiously. "It's not like you – at least, I don't think it is. She's a fine girl."

"What does the fine girl want?"

"What in the world's got into you? Why – oh, forget it. I'm not going to fight with you. Her back hurts – she's in considerable pain. Come and see it, please."

"I offered to see it last night. If she wants me now why doesn't she come and ask me?"

"Because she's scared of you, that's why," she said angrily. She stamped a foot in the frozen snow. "Will you go or not?"

I went. Below, I stripped off my gloves, emptied the ice out of them and washed my blistered, bleeding hands in disinfectant. I saw Marie LeGarde's eyes widen at the sight of my hands, but she said nothing: maybe she knew I wasn't in the mood for condolences.

I rigged up a screen in the corner of the room remote from the table where the women had been gathering and dividing out the remaining food supplies, and had a look at Margaret Ross's back. It was a mess, all right, a great ugly blue and purpling bruise from the spine to the left shoulder: in the centre, just below the shoulder blade, was a deep jagged cut, which looked as if it had been caused by a heavy blow from some triangular piece of sharp metal. Whatever had caused it had passed clean through her tunic and blouse.

"Why didn't you show me this yesterday?" I asked coldly.

"I -1 didn't want to bother you," she faltered.

Didn't want to bother me, I thought grimly. Didn't want to give yourself away, you mean. In my mind's eye I had a picture of the pantry where we had found her, and I was almost certain now that I could get the proof that I needed. Almost, but not quite. I'd have to go to check.

"Is it very bad?" She twisted round, and I could see there were tears in the brown eyes from the pain of the disinfectant I was rubbing on none too gently.

"Bad enough," I said shortly. "How did you get this?"

"I've no idea," she said helplessly. "I just don't know, Dr Mason."

"Perhaps we can find out."

"Find out? Why? What does it matter?" She shook her head wearily. "I don't understand, I really don't. What have I done, Dr Mason?"

It was magnificent, I had to admit. I could have hit her, but it was magnificent.

"Nothing, Miss Ross. Just nothing at all." By the time I had pulled on my parka, gloves, goggles and mask she was fully dressed, staring at me as I climbed up the steps and out through the hatch.

The snow was falling quite heavily now, gusting in swirling ghostly flumes through the pale beam of my torch: it seemed to vanish as it hit the ground, freezing as it touched, or scudding smoke-like over the frozen surface with a thin rustling sound. But the wind was at my back, the bamboo markers stretched out in a dead straight line ahead, never less than two of them in the beam of my torch, and I had reached the crashed plane in five or six minutes.

I jumped for the windscreen, hooked my fingers over the sill, hauled myself up with some difficulty and wriggled my way into the control cabin. A moment later I was in the stewardess's pantry, flashing my torch around.

On the after bulkhead was a big refrigerator, with a small hinged table in front of it, and at the far end, under the window, a hinged box covered over what might have been a heating unit or sink or both. I didn't bother investigating, I wasn't interested. What I was interested in was the for'ard bulkhead, and I examined it carefully. It was given up entirely to the small closed doors of little metal lockers let in flush to the wall – food containers, probably – and there wasn't a single metal projection in the entire wall, nothing that could possibly account for the wound in the stewardess's back. And if she had been here at the moment of impact, that was the wall she must have been flung against. The inference was inescapable – she must have been elsewhere at the time of the crash. I remembered now, with chagrin, that I hadn't even bothered to see whether or not she was conscious when we'd first found her lying on the floor.

Across the passage in the radio compartment I found what I was looking for almost immediately – I'd a pretty good idea where to look. The thin sheet metal at the top left-hand corner of the radio cabinet was bent almost half an inch out of true: and it didn't require any microscope to locate or forensic expert to guess at the significance of the small dark stain and the fibres of navy blue cloth clinging to the corner of the smashed set. I looked inside the set itself, and now that I had time to spare it more than a fleeting glance it was abundantly clear to me that the wrenching away of the face-plate didn't even begin to account for the damage that had been done to the set: it had been systematically and thoroughly wrecked.