If ever there was a time when my thoughts should have been racing it was then, but the plain truth is that they weren't. It was abominably cold inside the chilled metal of that dead plane, and my mind was sluggish, but even so I knew that this time I couldn't be wrong about what had happened. I could see now why the second officer had sent out no distress messages. I could see now why he had almost certainly been sending out his regular 'on route – on time' checks to base. Poor devil, he hadn't had much option -not with the stewardess sitting there with a gun on him. It must have been a gun. It was no consolation at all that the crash had caught her unprepared.

A gun! Gradually, ever so gradually, in infuriating slow-motion process, thoughts were beginning to click into place in my numbed mind. Whoever had landed that plane, landed it so skilfully into the blinding maelstrom of last night's blizzard, it hadn't been a dead man. I straightened, walked forward into the control cabin and shone my torch on the dead captain of the plane. As I'd noticed when I'd first seen him, he appeared to be completely unmarked, and I don't know whether it was some unconscious process of logical reasoning or some strange instinct that made me right away lift up the crackling ice-stiffened tunic j acket enough to see the black powder-ringed bullet hole in the middle of the spine. I had been expecting it, I had been uncannily certain that I would find such a hole, and find it just there: but my mouth was suddenly dry, dry as if I had drunk nothing for days, and my heart was thudding heavily in my chest.

I lowered the jacket, pulled it down into position, turned away and walked slowly towards the rear of the plane. The man the stewardess had called Colonel Harrison was still sitting as I had left him, propped up stiffly in a comer, as stiffly as he would remain there for heaven only knew how many frozen centuries to come.

The jacket was fastened by a central button. I undid it, saw nothing except a curious thin leather strap running across the chest, undid a shirt button, another, and there it was, the same deadly little hole, the same powder-ringed evidence of point-blank firing staining the whiteness of the singlet. But in this case the powder marks were concentrated on the upper part of the ring, showing that the pistol had been-directed in a slightly downward angle. On a hunch, but still like a man in a dream, I eased him forward, and there, less like a bullet hole in the jacket than an inconsequential rip one might easily overlook, was the point of exit, matched by an equally tiny tear in the padding of the upholstered seat behind. At the time, that carried no special significance for me. Heaven knows that I was in no mental frame of mind at the moment, anyway, to figure anything out. I was like an automaton, the movements of which were controlled by something outside me. I felt nothing at the time, not even horror at the hideous thought that the man's neck might well have been cold-bloodedly broken after death to conceal its true cause.

The leather strap across the man's chest led to a felt-covered holster under the arm. I took out the little dark snub-nosed automatic, pressed the release switch and shook the magazine out from the base of the grip. It was an eight shot clip, full. I replaced it and shoved the gun into the inside pocket of my parka.

There were two inside breast pockets in the jacket. The left-hand one held another clip of ammunition, in a thin leather case. This, too, I pocketed. The right-hand pocket held only passport and wallet. The picture on the passport matched the face, and it was made out in the name of Lieut.-Colonel Robert Harrison. The wallet contained little of interest – a couple of letters with an Oxford postmark, obviously from his wife, British and American currency notes and a long cutting that had been torn from the top half of a page of the New York Herald Tribune, with a mid-September date-mark, just over two months previously.

For a brief moment I studied this in the light of my torch. There was a small, indistinct picture of a railway smash of some kind, showing carriages on a bridge that ended abruptly over a stretch of water, with boats beneath, and I realised that it was some kind of follow-up story on the shocking train disaster of about that time when a loaded commuters' train at Elizabeth, New Jersey, had plunged out over an opened span of the bridge into the waters of Newark Bay. I was in no mood for reading it then, but I had the obscure, unreasonable idea that it might be in some way important.

I folded it carefully, lifted up my parka and thrust the paper into my inside pocket, along with the gun and the spare ammo clip. It was just at that moment that I heard the sharp metallic sound coming from the front of the dark and deserted plane.

For maybe five seconds, maybe ten, I sat there without moving, as rigid and motionless as the dead man by my side, bent right arm frozen in the act of folding the newspaper cutting into my parka pocket. Looking back on it, I can only think that my brain had been half numbed from too long exposure to the cold, that the shock of the discovery of the savagely murdered men had upset me more than I would admit even to myself, and that the morgue-like atmosphere of that chill metal tomb had affected my normally unimaginative mind to a degree quite unprecedented in my experience. Or maybe it was a combination of all three that triggered open the floodgates to the atavistic racial superstitions that lurk deep in the minds of all of us, the nameless dreads that can in a moment destroy the tissue veneer of our civilisation as if it had never been, and send the adrenalin pumping crazily into the bloodstream. However it was, I had only one thought in mind at that moment, no thought, rather, but an unreasoning blood-freezing certainty: that one of the dead pilots or the flight engineer had somehow risen from his seat and was walking back towards me. Even yet I can remember the frenzy of my wild, frantic hope that it wasn't the co-pilot, the man who had been sitting in the right-hand pilot's seat when the telescoping nose of the airliner had folded back on him, mangling him out of all human recognition.

Heaven only knows how long I might have sat there, petrified in this superstitious horror, had the sound from the control cabin not repeated itself. But again I heard it, the same metallic scraping sound as someone moved around in the darkness among the tangled wreckage of the flight deck, and as the touch of an electric switch can turn a room from pitch darkness to the brightness of daylight, so this second sound served to recall me, in an instant, from the thrall of superstition and panic to the world of reality and reason, and I dropped swiftly to my knees behind the high padded back of the seat in front of me, for what little shelter it offered. My heart was still pounding, the hairs still stiff on the back of my neck, but I was a going concern again, my mind beginning to race under the impetus invariably provided by the need for self-preservation.

And that self-preservation entered very acutely into it I did not for a moment doubt. A person who had killed three times to achieve her ends -1 had no doubt at all as to the identity of the person in the control cabin, only the stewardess had seen me leave for the plane – and protect her secret wouldn't hesitate to kill a fourth. And she knew her secret was no longer a secret, not while I lived, I had stupidly made my suspicions plain to her. And not only was she ready to kill, but she had the means to kill – of the fact that she carried a gun and was murderously ready to use it I'd had grisly evidence in the past few minutes. Nor need she hesitate to use it: apart from the fact that falling snow had a peculiarly blanketing effect on all sound, the south wind would carry the crack of a pistol-shot away from the cabin.