"But if there's no haemorrhaging?" she persisted. "If the damage is no worse than what you think, what you see?"

"Fifty-fifty. I wouldn't have said so a couple of hours ago, but he seems to have quite astonishing powers of resistance and recuperation. Better than an even chance, I would say – if he had the warmth, the food, the skilled nursing he would have in a first class hospital. As it is – well, let's leave it at that, shall we?"

"Yes," she murmured. "Thank you."

I looked at her, looked at the washed-out face, the faint blue circles forming under her eyes, and almost felt touched with pity. Almost. She was exhausted, and shivering with cold.

"Bed," I said. "You're dying for sleep and warmth, Miss– I'm so sorry, I forgot to ask your name."

"Ross. Margaret Ross."

"Scots?"

"Irish. Southern Irish."

"I won't hold it against you," I smiled. There was no answering smile from her. Tell me, Miss Ross, why was the plane so empty?"

"We had an 'X' flight – an extra or duplicate charter for an overflow of passengers – out from London yesterday. Day before yesterday it is now, I suppose. We just stayed the night in Idlewild and had to return after we'd slept. The office phoned up people who had booked out on the evening plane, giving the chance of an earlier flight: ten of them accepted."

"I see. By the way, isn't it a bit unusual to have only one stewardess aboard? On a trans-Atlantic flight, I mean?"

"I know. There's usually two or three – a steward and two stewardesses – or two stewards and a stewardess. But not for ten people."

"Of course. Hardly worth stewarding, you might say. Still," I went on smoothly, "it at least gives you time for the odd forty winks on these long night-flights."

"That wasn't fair!" I hadn't been as clever as I thought, and her white cheeks were stained with red. "That's never happened to me before. Never!"

"Sorry, Miss Ross – it wasn't really meant as a dig. It doesn't matter anyhow."

"It does so matter!" Her extraordinary brown eyes were bright with unshed tears. "If I hadn't been asleep I would have known what was going to happen. I could have warned the passengers. I could have moved Colonel Harrison to a front seat facing the rear – "

"Colonel Harrison?" I interrupted sharply.

"Yes. The man in the back seat – the dead man."

"But he hadn't a uniform on when – "

"I don't care. That was his name on the passenger list.... If I'd known, he wouldn't be dead now – and Miss Fleming wouldn't have had her collar-bone broken."

So that's what has been worrying her, I thought. That accounts for her strange distraught behaviour. And then a moment later I realised that it didn't account for it all – she had been behaving like that before ever she had known what had happened to any of the passengers. My slowly forming suspicions came back with renewed force: the lady would bear watching.

"You've nothing to reproach yourself with, Miss Ross. The captain must have been flying blind in the storm – and we're more than 8000 feet up here. Probably he'd no knowledge of what was going to happen until the actual moment of crashing." In my mind's eye I saw again the doomed airliner, landing lights on, circling our cabin for at least ten minutes, but if Miss Ross had any such thing in her mind's eye, it was impossible for me to detect it. She had no idea at all – or she was an extraordinarily good actress.

"Probably," she murmured dully, "I don't know."

We had a hot and satisfying meal of soup, corned meat, potatoes and vegetables – everything out of cans, but passable enough for all that. It was the last satisfying meal that our guests – or ourselves, for that matter – were likely to have for some considerable time to come, but I felt the moment unpropitious for breaking that sort of news. Time enough for that tomorrow – or later in the day, rather, for it was now already after three o'clock in the morning.

I suggested that the four women sleep in the top bunks – not from any delicacy of sentiment but because it was at least twenty-five degrees wanner there than it was at ground level, and the proportional difference would increase as the night wore on after the stove had been put out. There were some half-hearted protests when they learnt that I intended to shut down the fire, but I didn't even bother arguing with them. Like all people who have lived for any length of time in the Arctic, I had an almost pathological dread of fire.

Margaret Ross, the stewardess, refused the offer of a bunk, and said she would sleep by the injured pilot, lest he should wake and want anything during the night. I had intended doing that myself, but I saw her mind was set on it, and though I felt unaccountably uneasy about the idea, I raised no objection.

That left five empty bunks among six men – Jackstraw, Joss and I could sleep reasonably enough in our furs. Inevitably, there was some magnanimous argument over the allocation of these bunks, but Corazzini settled the argument by producing a coin and beginning to toss for it. He himself lost in the end, but accepted defeat and the prospect of a cold uncomfortable night on the floor with amiable grace.

When they were all settled down, I picked up a torch and our weather log book, glanced at Joss and made for the trap. Zagero turned in his bunk to look at me.

"What gives, Dr Mason? Especially at this hour of night, what gives?"

"Weather reports, Mr Zagero. That's why we're here, remember? And I'm already three hours late with these."

"Even tonight?"

"Even tonight. Continuity is the most important thing in weather observation."

"Sooner you than me." He shivered. "If it's only half as cold outside as it is in here."

He turned his back, and Joss rose to bis feet. He'd correctly interpreted my look, and I knew he was consumed with curiosity.

"I'll come with you, sir. Better have a last look at the dogs."

We didn't bother looking at either the dogs or the weather instruments. We went straight towards the tractor and huddled under the tarpaulin for what miserable shelter it could afford. True, the wind had eased, but it was colder than ever: the long winter night was beginning to close down on the ice-cap.

"It stinks," Joss said flatly. "The whole set-up stinks."

"To high heaven," I agreed. "But it's finding out where the smell comes from that the trouble lies."

"This fairy tale of yours about magnetic storms and compasses and radios," he went on. "What was the idea?"

"I'd previously said I knew something they didn't. I did. But when it came to the bit I knew I'd be better to keep it to myself. You know how this damnable cold slows up your mind -1 should have realised it sooner."

"Realised what?"

That I should keep it to myself."

"Keep what, for heaven's sake?"

"Sorry, Joss. Not trying to build up suspense. The reason none of them knew anything about the crash until after it had happened is that they were all doped. As far as I could see, all of them, or nearly all, were under the influence of some sleeping drug or narcotic."

In the darkness I could almost feel him staring at me. After a long time he said softly, "You wouldn't say this unless you were sure of it."

"I am sure of it. Their reactions, their dazed fumbling back to reality – and, above all, the pupils of their eyes. Unmistakable. Some kind of sleeping tablet mixtures, of the fast-acting kind. What is known to the trade, I believe, as Mickey Finns."

"But – " Joss broke off. He was still trying to orientate his mind to this new line of thought. "But – they would be bound to know of it, to be aware that they had been doped, when they came to."

"In normal circumstances, yes. But they came to in what was, to say the least, most abnormal circumstances. I'm not saying that they didn't experience any symptoms of weakness, dizziness and lassitude – they must have done – and what more natural than that they should ascribe any such unusual physical or mental symptoms to the effects of the crash. And what more natural, too, than that they should conceal these symptoms as best they could– and refrain from mentioning them? They would be ashamed to admit or discuss weaknesses – it's a very human trait to show to your neighbours the very best face you can put on in times of emergency or danger."