I am going stalking, with my father, and together we are going to hunt for deer in the depths of the Scottish highlands. This is partly some kind of male bonding exercise over rifles and blood and whisky, and partly because my father wants to get away from his wife, and partly because he enjoys the taste of fresh venison. We are met at the estate we're going to stalk on by the gamekeeper. He is sixty-four, and his face has a square-jawed reliability that is comforting. His is palpably rugged and his patched, mismatched clothes make me appreciate, in a flush of shame, how very green my new jacket is. The gamekeeper treats my father and me with a wry tolerance that rapidly thaws to open good humoured amusement at the way we play at being countrified, which is to say, ineptly. Whilst running a scornful eye over my beard and ponytail, he runs us through what we're using – a Winchester .270, Remington shells and a Zeiss scope. We do some target practice and I remember to shoot between heartbeats, and at a hundred yards I score a perfect bull's eye.

The gamekeeper's estate is a valley about four miles end to end, five hundred yards deep, covered in heather and fringed by a loch on one side and mountains on the other. The heather flowers are pink and white and purple and home to grouse and huge furred caterpillars. The deer are wild, and whether or not you'll find any is down to luck and a gamekeeper's skill. To get around, the gamekeeper uses his unapologetically cuboid truck, made up of a 2CV, a Landrover, plywood, and sheet metal. About halfway along the valley floor, the gamekeeper stops abruptly, gets out his Victorian telescope, and peers, faraway. Aye, he says, his burr thick to the point of self-parody, there's twenty-seven of them on that ridge, and they're facing east. Deer can detect you in three ways: they can see you, hear you, and smell you. This means that to stalk successfully you must approach them from downwind, slowly, and through good cover.

For two hours we traverse the valley side, moving from one peat bog to another, silently. The day is windless and overcast – this means that our smell may or may not carry. Windless it worst, because it is unknowable. A set wind you can always walk into, but with windlessness you risk being scented a mile distant. The deer seem improbably large silhouetted on the ridge. We must be very close, but ten minutes later I ask and we are still four hundred yards off, but now we are stuck too far off to shoot but with no cover to move closer under. A sudden mist drops and we dash the next two hundred yards over open ground covered by impenetrable cloud. When we reach the next peat bog, the deer have started to move again, but now towards us, and at seventy yards the herd is dangerously close, because a panicked herd is bad news to be too near to. So we drop back down the hill, and retrace our steps, and then get closer to the deer again, and then drop back again, and so on. I am sweating heavily and worry that this frantic running just makes us smell stronger. Finally, as the mist clears and a heavy rain sets in, the gamekeeper stops still just underneath the crest of a contour.

The gamekeeper motions me up onto the hummock, and points. There above me are eighty deer, moving slowly across us. I have no idea how far away they are, but seeing first hand a herd, a real live herd of wild, unowned animals takes my breath away for a few seconds. I lift myself towards the rifle. By the time I've found the stag I've been told to take, I've lost my footing and have slid down, and brought myself back up again. The rain has coated my glasses and both ends of the sight and I cannot see. I lift my hood to protect my face, but all the water that has gathered on it just courses down off it and finds its way into my shirt. The stag has now moved much too far away, and so to compensate I have to aim a few inches high to hit his heart. At a kilometre a second, a few inches is a lot of compensation to make. I am aware that the trigger is far too light for something this important. And then everything stops, and the bullet has left me, and I close my eyes. Because even though at last the thing has started, or finished, I can't tell which it is.

Whether it's the wind or I jerk the trigger or I just aim badly, I hit the stag about six inches behind its heart, in its lungs. The whole herd starts, and the hillside is cleared fast. The stag sways but doesn't drop. Aye, he says. He'll be drowning in his own blood about now. Don't worry; it's about par for the course, and there's nothing that can be done. I shouldn't have asked you to take such a long shot, but you made good of it, don't worry, let's have some sandwiches while we're waiting. It seems that my father is getting out sandwiches at a fantastically busy rate. I watch the rain beading on my jacket sleeve. The beads of water are so tiny, so irrelevant: I wish I could just sit here and watch them. I can hear my father eating his brie and tomato scones – it seems very loud. The gamekeeper goes to make sure the stag is dead and a second shot sounds through the valley. And then I go to see.

Slumped on its front, the stag is beautiful. Its eyes are enormous, and a milky film is already covering them. There is blood on the stag's teeth. The horns tower, its pelt is thick but soft to the touch, and for a moment I stand agape. I am unable to confront myself with the fact that is so presented to me. This animal is real and it is in front of me and – and this is strangest of all – I killed it. The gamekeeper, enjoying my shock, sets to work, opening up its intercostal muscles and letting the blood inside run out, an appallingly dark shade of crimson. As he turns this mass, this still-warm, lifeless mass over the air is pushed from its lungs with a low, snorting groan. Bending down, he collects some blood on his hand, and daubs me with it, thickly, until I can feel most of my face smeared with its wetness. As I am blooded, I stand there transfixed, incredulous, reverential. Is this what it takes to be a hunter? A hot, panicked fumble in the rain? I can feel the blood coagulating as a gathering tightness on my cheeks, and every time I smile I can feel the bloodstains cracking, minutely.

Splaying the stag's legs, the gamekeeper tells a funny story about the time an Italian guest fucked a hind he'd shot as a matter of course. I laugh because that's what you do when a story is funny. He runs his knife along the stag's belly and pulls out its intestines, which seem to go on for a very long time. The stag's stomach is bloated with heather. The intestines snap and the gamekeeper swears and cuts what's left out by slicing around its colon from outside. The air smells of blood and shit and wet fur and otherness. This fourteen stone thing lies, half processed and with its blood steaming in the gentle sunlight. I know the arguments for catching your meat this way inside out; I have rehearsed and examined them and they are good ones: rational, fair. And certainly, there's no way I'm about to become a vegetarian – that would be childish. But something in this sight defies reason, and outflanks every explanation I can make.

The gamekeeper goes down the hill to get the truck, and my father and I wait beside the disembowelled creature. In what is perhaps intended as a gesture signifying empathy, my father hands me his monogrammed leather and silver hipflask, and says, when killing an animal, you always feel this real sense of responsibility, don't you? I'm surprised by the swiftness with which a very adolescent anger that runs through me at this. I make a small noise he chooses to interpret as assent, and then he falls silent, perhaps looking at the loch stretched out far beneath us. I am desperate for the truck not to arrive, because once this stag leaves the hill he is irrevocably ours, but while he is sprawled beside me on the pink and white heather there is a feeling of mutability, or at least that what has begun doesn't have to be completed. Before I hear the truck, we are thankfully wrapped in fog again, and its womb of inconsequence and delimitation comforts me.

It is profoundly saddening to travel over uneven ground with a large dead animal. With each jolt of the ground the pliant haunches flex while the tongue lolls absurdly at the end of a twisted neck. The rain is now lashing at us from the bottom of the valley, and the blood on my face mixes with it and runs down, into my eyes and then over my cheeks and the furred swell of my upper lip, underneath which it comes to rest on my tongue, warmly. I am standing in the back of the truck, blinded and unsteady, and this salty pinkish fluid is gathering in my mouth, tepid and nauseating. As it pools there, it tastes as though I have been crying. Suddenly, I am unable to swallow.