"Not knowing that I was there waiting to oblige Smallwood," I said bitterly. I shook my head in turn. "It's obvious now, all too obvious. How Corazzini damaged his hand in the shack – not by saving or trying to save the radio but by accelerating its fall after he'd pushed the hinges in. How and why he lost the toss and had to sleep on the floor – to give him a chance to smother the second officer."

"What you might call a good loser," Zagero said grimly. Then he gave a short laugh. "Remember when we buried the second officer? I wonder what Smallwood's burial service would have sounded like if we'd really been close enough to hear?"

"I missed that," I nodded. "I missed the suggestion you made inside the plane that we should bury the murdered men – if you had been guilty you'd never have dared make that suggestion for then the way these men died would almost certainly have been discovered."

"You missed it," Zagero said feelingly. "How about me – /said it, and I never even thought of it till now." He snorted. "Boy, am I disgusted with myself. As far as I can see the only thing I knew that you didn't was that Corazzini clouted our friend Smallwood back in the pass there simply in order to throw suspicion on me: but, then, I knew that even trying to tell you that would have been crazy."

There was a long moment's silence, while we listened to the rise and fall of the Citroen's exhaust note in the gusting, strengthening wind, then Solly Levin spoke.

The plane," he said. "The fire – how come?"

"There was enough high-octane fuel in its tanks to take Hillcrest's Sno-Cat a couple of thousand miles," I explained. "If Hillcrest's tanks had been empty when he arrived back at base and if he'd found out right away that the spare fuel in the tunnel had been doctored – well, it wouldn't have taken him long to siphon out the stuff in the plane. So, no plane."

The silence this time was even longer, then Zagero cleared his throat, as if uncertain how to begin.

"Seeing explanations are in the air – well, I guess it's time we made one too." Zagero, to my astonishment, sounded almost embarrassed. "It's about the phony conduct of that phony character to your left, Doc, one Solly Levin. We'd plenty of time to talk about it when we were lashed to this damned sledge all of last night and – "

"Come to the point," I interrupted impatiently.

"Sorry." He leaned across to Solly Levin. "Want I should make a formal introduction, Pop?"

I stared at him in the darkness.

"Did I hear – "

"Sure you did, Doc." He laughed softly. Top. The old man. The paternal parent. Says so on my birth certificate and everything." He was enjoying himself vastly. "Confirmation on the right here."

"It's perfectly true, Dr Mason," Solly Levin smiled. The dreadful Bowery accent was quite 'gone, yielding place to a crisper, more decisive version of Zagero's cultured drawl. "I'll put it briefly. I'm the owner and managing director – or was till I retired a year ago – of a plastics factory in Trenton, New Jersey, near Princeton, where Johnny managed to acquire a splendid accent and very little else. It was not, I might add, Princeton's fault; Johnny spent most of his time in the gymnasium, nursing his – ah – pugilistic ambitions, much to my annoyance as I wanted him to take over from me."

"Alas," Zagero put in, "I was almost as stubborn as he is himself."

"A great deal more so," his father said. "So I made him a proposition. I'd give him two years – it seemed enough, he was already amateur heavyweight champion – to prove himself, and at the end of that time if he hadn't made it he was to take his place in the factory. His first manager was as corrupt as they come and Johnny literally kicked him out at the end of a year. So I took over. I'd newly retired, I'd time on my hands, I'd a very strong vested interest in his well-being apart from the fact that he was my son – and, quite frankly, I'd begun to see that he really was going to get to the very top." He broke off there – so I took the opportunity to interrupt.

"Zagero or Levin. Which is it?"

"Zagero," the elder man answered.

"Why the Levin?"

"Some state and national boxing commissions refuse to permit a close relative to be either manager or second. Especially second. So I used an alias. A practice by no means uncommon, and officially winked at. A harmless deception."

"Not so harmless," I said grimly. "It was one of the worst acting performances I've ever seen, and that was one of the primary reasons for my suspecting your son and, in turn, for Corazzini and Smallwood getting away with what they did. Had you come clean earlier on, I would have known that they were bound, even in the absence of all possible evidence, to be the guilty men. But with Solly Levin – I'll find it very difficult to think of you as Mr Zagero, I'm afraid – with Solly Levin sticking out like a sore thumb as an obvious phony – well, I just couldn't leave you two out of the list of suspects."

"I obviously modelled myself on the wrong person – or type of person," Levin said wryly. "Johnny ribbed me about it all the time. I'm deeply sorry for any trouble we may have caused, Or Mason. I honestly never looked at it from your point of view, never realised the dangers involved in maintaining the impersonation – if you could call it that. Please forgive me."

"Nothing to forgive," I said bitterly. "A hundred to one I'd have found some other way of messing things up."

Shortly after five o'clock in the evening Corazzini stopped the tractor – but he didn't stop the engine. He came down from the driver's seat and walked round to the cabin, pushing the searchlight slightly to one side. He had to shout to make himself heard above the roar of the tractor and the high ululating whine of the still-strengthening blizzard.

"Half-way, boss. Thirty-two miles on the clock."

"Thank you." We couldn't see Smallwood, but we could see the tip of his gun barrel protruding menacingly into the searchlight's beam. "The end of the line, Dr Mason. You and your friends will please get down."

There was nothing else for it. Stiffly, numbly, I climbed down, took a couple of steps towards Smallwood, stopped as the pistol steadied unwaveringly on my chest.

"You'll be with your friends in a few hours," I told Smallwood. "You could leave us a little food, a portable stove and tent. Is that too much to ask?"

"It is."

"Nothing? Nothing at all?"

"You're wasting your time, Dr Mason. And it grieves me to see you reduced to begging."

"The dog sledge, then. We don't even want the dogs. But neither Mahler nor Miss LeGarde can walk."

"You're wasting your time." He turned his attention to the sledge. "Everybody off, I said. Did you hear me, Levin? Get down!"

"It's my legs." In the harsh glare of the searchlight we could see the lines of pain deep-etched round Levin's eyes and mouth, and I wondered how long he had been sitting there suffering, saying nothing. "I think they're frozen or sleeping or something."

"Get down!" Smallwood repeated sharply.

"In a moment." Levin swung one of his legs over the edge of the sledge, his teeth bared with the effort. "I don't seem to be able – "

"Maybe a bullet in one of your legs will help," Smallwood said unemotionally. "To get the feeling back."

I didn't know whether he meant it or not. I didn't think so -gratuitous violence wasn't in character for this man, I couldn't see him killing or wounding without sound reason. But Zagero thought differently. He advanced within six feet of Smallwood.

"Don't touch him, Smallwood," he said warningly.

"No?" The rising inflection was a challenge accepted, and Smallwood went on flatly: "I'd snuff you and him like a candle."

"No!" Zagero said, softly and savagely, the words carrying clearly in a sudden lull in the wind. "Lay a finger on my old man, Smallwood, and I'll get you and break your neck like a rotten carrot if you empty the entire magazine into me." I looked at him as he crouched there like a great cat, toes digging into the frozen snow, fists clenched and slightly in advance of him, ready for the explosive leap that would take him across that tiny space in a split second of time and I believed he could do exactly what he said. So, too, I suspected, did Smallwood.