When you go to your chiropractor, he first asks you to take off your necklace, then he puts his hands around your neck and squeezes the vertebra at the base of your skull. The vertebra feels tender, as if bruised.

‘Can you tolerate this?’ he asks. You try to nod. You hadn't known that vertebrae could reach so far up, right to the back of the brain.

‘Oh yes. The vertebrae go all the way up to the head, like a ladder,’ your chiropractor says. ‘Humans are really just highly evolved ladders.’

You like this idea - that the human body is first and foremost a structure. We are like kitsets or foldaway beds. He says that the ribs, too, go up a long way, into the soft fleshy parts of the back near the armpits.

You lie face down on the stretcher. It's a low vinyl-covered table with a headrest that has two fabric-covered sausages on each side. Listen, it's hard to describe. There's no other piece of furniture like it. Let's just say that when you lie down, your face is squished in the centre of the two sausages, as if you've fallen asleep in the middle of a book, woken up, and found yourself in a room with a tall man. You close your eyes and in a muffled face-down voice you talk to your chiropractor: the foul spring weather, how you were knocked off your bike last week, maybe how you're thinking of quitting your job. Your chiropractor is a friendly, earnest man with a passion for bones; you've known him two years. But you're not really paying attention to this conversation. It's the other conversation you're interested in — the one between his hands and your back. Your back is listening. You know his hands are close when you feel a tingle in the skin on your back, as if the nerves in your spine were reaching up to the surface. This is your skin's reception: nerves picking up faint signals from approaching hands.

Your chiropractor begins to knead all along your spine. You don't know what he's looking for but you're confident he'll find it and fix it; he always does.

It sounds like torture when you try to describe it to other people. You come here to have your spine shoved or your head wrenched sideways. Better to talk about the lightness, the tallness, you feel when you leave. Some people are so afraid of chiropractic that they become afraid of you if you mention your chiropractor. Everybody knows that the nerves that govern a person's soul all live in the spine and neck. If you mess with them, you will die! Or be paralysed. Your jaw will seize and your eyes will stare frozenly. Chiropractic will never escape those connotations of torture. Mostly it's because we think bones should be silent. When we hear them moving, we think of pain, of permanence.

‘Those aren't your bones making that noise,’ says your chiropractor, ‘it's actually gas.’ Oh my god, you think. But he says it is just the sound of tiny bubbles of nitrous oxide, nothing more than laughing gas, releasing from the bone joint with a pop! The bones themselves stay very quiet, the introverts of the body.

Your chiropractor is so devoted to his field that if you ever ask a question, it's as if he's afraid you've stopped believing and he must persuade you all over again. So now he explains that the spine is a scaffold, or a great bridge between your nerves and your body, holding all of you upright so that the great work of art that is the body can commence motion. He laments the way people say, ‘I've put my back out,’ as if a back were something you could hold at arms' length and leave on the curbside. ‘The problem with people,’ he says, ‘is that they think of themselves as bits and pieces. As if your head lives on a different continent from your feet, or your eyes live on a different planet from your heart. Well, for some people perhaps that is true. But most of us live in the one body, wouldn't you agree?’ He says that if your scaffolding is askew, then the rest of your body and your mind won't work. Bits start sliding, shaking, falling. That's where the manipulations come in. All day long, your chiropractor is fixing, fixing, fixing.

‘I'm basically a mechanic,’ he says, with delight, as if he has only just realised this. ‘Now, I'm not saying there aren't some essential differences between the human body and, say, an airplane. But there aren't very many!’ He pauses. He's found something, some vertebrae that have lost their way. ‘Deep breath in?… and deep breath out —’ and he pushes your spine so hard it crackles electrically.

Next, he has you roll to the left. He rearranges your arms so that you're in a relaxed foetal position. Then he presses one of his knees against your thigh — he has large square knees that dwarf your smallish round ones — and pushes, pushes, pushes. There is a faint cracking sound, like roots pulling up. You imagine fissures appearing in your body, as if during a quake.

‘Can you tolerate this?’

You keep your eyes half closed but you can see him looming above you like a pylon. ‘Yup. I'm fine.’ You roll to the right and he cracks open the other side.

Sometimes when you're lying face down on the table, he will ask you a question. The question will be something like, ‘What do you think is the difference between a thought and an emotion?’

Of course you will struggle to answer this but you will try to sound as if you think about this kind of thing all the time. ‘Well, a thought is only ever in your head. An emotion can be, I don't know, in other places in your body. It can be everywhere. It's kind of shapeless, fluid. It can feel almost physical, like a pain.’

He never agrees or disagrees with what you say; instead he pauses for a moment — you can feel him thinking, through his hands — and then says something like, ‘Could you say, perhaps, that an emotion is a physical thought?’

You wish you had thought of this. ‘Yeah! Exactly. An emotion can make you feel sick or sweaty or excited, and those are all physical expressions of different thoughts.’

Talking like this makes you wriggle around a bit on the stretcher, and your chiropractor gently straightens you out or put your arms back down at your side.

In the past you'd thought that lying here was a serious risk. Besides the fact that your chiropractor is much bigger and stronger than you — long legs, long arms, a large bald head and a perfectly handsome face — you'd secretly believed that trusting any person to modify your skeleton was crazy. Even if that person is someone you have known and trusted for years, as you would a close friend, it does not mean you should trust him with your life.

Now you suspect that you are beginning to. When you're stretched out on this vinyl table and the sun is angling in through the top window, when you see that egg-coloured elasticated spine hanging in the corner, most of all when your chiropractor puts his hands on your back and tells you what he knows about your bones, then the idea of risk becomes only that — an idea. Something amoebic, rootless, spineless. And there's something else, too. This feeling that happens when you are touched. It is a kind of trust, or a wish for trust, or something else.

‘That back is good to go. Sit up, now,’ he says. You do, fuzzy-haired, blinking. ‘Let's take a look at that neck of yours.’

‘OK.’ And you sit very still.

He looks down at you and takes your head in both hands. He presses your throat just under your jawline, the bones at base of your skull, and the tender spots around your ears. He gazes over the top of your head. You can't help thinking at this point that maybe, he will lean down and kiss you. There is too little difference between the beginning of a kiss and the beginning of a neck adjustment. You stare at his face foolishly. ‘Relax,’ he says.

After a loaded pause, he yanks your head to the left. Snap. Then he yanks your head to the right. The sound is a sheet of bubble wrap popping. Your chiropractor steps back and nods, finally looking you in the eye.

‘You're good at those,’ he remarks with a wry smile. ‘Most people scream a little bit.’

You try out your new neck: it feels freer. Your head sits more lightly, an egg balanced in a spoon.

You're annoyed by your lapse into impropriety. Thoughts of romance are so predictable, so amateur. Why can't you feel nothing? It would not be a problem if you could think of your body as an airplane, as your chiropractor does, or simply a lattice of sinew and bone, muscle, soft tissue, nerve fibers. A body with an ordinary skeleton inside it; it could be anyone's.

To mask your lapse, you ask another question. ‘Do you ever get annoyed about sceptics? I mean, do you have people who come in and say they think it's all phony but their friend told them to come, that kind of thing?’

‘Oh,’ he says — and you can hear the pragmatism in his voice; he's used to being the reasonable one among the disbelieving — ‘there's certainly a lot of folklore around. People think they've slipped a disc. They think they've got a nerve floating around in their spine, you know, just drifting around in there. Sometimes when I treat people's backs, they think I've broken them in half! Or they think I'll give them a stroke or a heart attack. But look, I don't waste my energy getting frustrated any more.’

Your appointment is over. You take your necklace from his desk and put it back on. You always feel a little awkward doing this; this small, intimate putting-on in your chiropractor's office. Briefly you are a woman in a movie.

‘OK,’ he says, frowning into his diary. ‘How are you for next Thursday at noon?’ Between his eyes there's a furrow. How old is he? Thirty? A well-preserved forty? His eyes are steely and clear: you see perfect health there. Everything is in its right place in him, as you'd expect.

‘Thursday's good for me.’

After paying up — $25 for fifteen minutes, which you can't really afford — you smile goodbye and he puts his hand lightly on your shoulder, as if placing a full stop there. ‘Thanks, Ash. Have a good day eh?’ His eyes can only be described as … nice. He is a genuinely nice man who is interested in people: their bones, their physical thoughts. And you feel the thing you so often feel when you meet someone like this — that you're not worthy of this niceness.

When you're walking down the stairs, you feel a suspicious glow in your belly. It's then that you realise: you've got to stop this! Look, your chiropractor is basically a mechanic and you are a vehicle in occasional need of repair. When it comes to being re-adjusted, that is all we need to be. A hairdresser touches hundreds of heads. A doctor listens to hundreds of hearts. None of this means anything beyond what it is. The point is, you no longer feel numb. Your nerves know something. As you walk out onto the street, you feel lighter.  

A month or so down the line, you're greeted by a young woman with a shiny brown ponytail. ‘Hi!’ she says and shakes your hand. ‘I'm Cath. Tobias is away today.’ Something in her voice gives you pause but you don't pry. Cath has strong, knuckly hands and enviable self-confidence. She adjusts your lower back, hips, neck, and the sticky-outy rib that is causing your sore shoulder. You leave feeling slightly delirious.

At your next appointment — with Cath, again — she tells you that Tobias is in hospital. He has a tumour. ‘I just wanted to let you know,’ she says. ‘It's early days yet. He's doing fine. We'll just see what happens.’

You think of your chiropractor in hospital, prone for hours, waiting for tests, waiting to see what happens. Who does he trust with his life? You wonder what it would be like to visit him. You could take flowers, a book, a card, sit on the chair beside his bed. But, of course, you don't visit.

At each appointment over the next months, Cath tells you he's doing okay. Then she stops mentioning him, and simultaneously you stop wondering. Cath has warm, friendly eyes and a ready smile. She knows her bones inside out. She knows the parts of your neck that store tension in gnarls, she knows all about the wayward rib, and she knows that there are two small muscles on either side of your lower spine that are always sore. At first you'd thought they were your kidneys. Sometimes it seems that you don't know your own body very well at all. You need someone else to tell you what it is, and to sort it out so that you can carry on.

At the vegetable markets the air is cool from a night of rain. There are broken stalks and leaves scattered on the asphalt among the stalls, and people who gather and bend and fill seamy plastic bags. You're looking for tomatoes when you see a bald head bending towards a crate full of apples. You hold back for a second, then say, ‘Hello, Tobias.’ He looks at you for a few seconds, searching, then he smiles and says hello. ‘How are you doing? How's that neck?’

‘Pretty good. Cath has been keeping me in line.’ Then you feel yourself go shy and fumbling. ‘I heard that you've been unwell. How are you?’

‘I'm fine now,’ he says, nodding. And he does look fine, if you look at the surface of his face and don't know about the tumour; in fact his eyes look particularly bright and clear. He has even grown a little goatee. You think how good it is to see him. You think: the tumour must be gone. You talk about the abundance of cheap avocados. There are new stalls that sell French crepes, Yorkshire pies, and boutique beer; it's all very European, this car park. You mention the book he once recommended you called A New Earth — which you thought was silly but which you say you liked — and you tell him about your new flat; you had to pay a special visit to Cath after lifting all those boxes of books, ha ha! He's holding a canvas bag; bushels of celery stick out the top. There is very little movement in his body. He stands quite stiffly with his head bowed toward your mouth. Then there's a quiet moment and the wind picks up, so you say OK, well. He says it was good to see you and puts his hand on your shoulder, and you each wander away to different stalls. You mindlessly spend the rest of your money on half a pumpkin and two kumara that are so large they look mutant; huge dark gnarled things with frizzy antennae, they look like they should never have come up out of the ground. Now you have to eat them, and you've spent all your money.

Your chiropractor floats into your head at odd moments during the next few weeks. Boring thoughts, like I wonder what he made with all the celery and What is a tumour made of? But a few months later at your appointment, Cath tells you, with mist in her kind eyes, that he has died.