Friday 7 November, 3.42 p.m.

My life runs like clockwork. Nothing can go wrong, ever, because it could mean the difference between life or death. And I’m not joking.

When the school bell signals freedom at 3.45 p.m. exactly, I always make a break for it. I run and I run, never stopping. Our house is 1.8 miles away, and I must be home by five minutes past four. No ifs or buts. There’s no other way to make it on time except to run the whole way. Whatever it takes, I can’t be late. I will not be late.

It doesn’t matter where my last lesson of the day takes place. Wherever I am, I know the quickest way out of the school building. I learned the location of every classroom, staircase and exit the first day I arrived at Hayesford Secondary School in September, just two months ago.

Last lesson this Friday afternoon is a double dose of French. Hiding away in a corner, still and silent, merging into the background, I keep my head down so the teacher doesn’t notice me. It’s what I’m good at. As usual, I watch the minutes tick away on the clock, and I count them down.

I have a routine, and today is no different. Three minutes before the bell, I slip books, pens and papers into my bag underneath the table. My jacket is already rolled up and bundled inside, placed there at lunch time. I grasp the handles of my bag tightly. No one notices.

Come on, I think, clockwatching obsessively, counting down inside my head. Come on. The sixty seconds between 3.44 and 3.45 p.m. seem like six hundred, always.

Then the bell rings and I snap my laptop shut, although I leave it on the desk because it’s not mine; it belongs to the school – I can’t afford my own. I slide from my chair, and before my classmates have even begun to pack away their stuff, I’m through the door.

Behind me Mrs Kaye is still talking. ‘Have a good weekend, everyone, and don’t forget, I want your homework in by—’

But I’m gone, expertly pulling my jacket from my bag and slipping it on as I speed down the corridor. Homework is the very least of my problems.

Quite often I’m first into the playground with a clear run to the open gates. But if my last lesson of the day is at the other end of the school, as it is today, there will already be students outside before I get there, and they keep coming, flowing endlessly out of the building from every exit. They hang around in groups, chatting, laughing, texting, snapping selfies, standing in my way, slowing me down as I swerve round them.

Today one of the big boys tries to trip me up as I fly past, for a laugh. But I’m ready for him, hurdling his outstretched leg, and then I’m out of the playground into the street. After a mild, golden autumn, winter is creeping in, curling her freezing fingers around us, and already the light is fading into dusk. But my heart lifts because today is Friday and I’m free of school for two whole days. Once I get home, though, I won’t leave the house except to buy food and – well, you don’t need to know the details.

The school buses wait at the gate. One of them stops near my home and would get me there in just ten minutes. But I don’t have the money for the bus. I never do.

I run to a strict schedule. It should take four minutes to reach the shops a few streets away, so when I get to Tesco Express, I glance at my watch. Four minutes exactly.

I’m flying along so fast that my inky-black hair, which has never been cut and reaches below my waist when it’s loose, is slipping from its ponytail. I neatly sidestep the bustling shoppers, wondering briefly what they think of me. I know what they see – a small, slight figure with dark eyes, too big in a thin face, and a permanently anxious expression.

I dodge round the long queue for the cash machine outside the bank.

‘Look where you’re going!’ a woman in a smart coat snaps at me. I was never anywhere near her, but she has a narrow, mean mouth and probably speaks like that to everyone she meets. At times I long for a big family and lots of friends. Then someone like the mean woman comes along, and I’m glad it’s just me and Mum.

To the post office on the corner – five minutes. I’m still on schedule.

Then anxiety grips and twists my insides as I see that the pavement outside the post office has been dug up by workmen. The area is cordoned off and a sign directs people to a narrow, single-file walkway. I stop to assess the situation in a split-second. Is it quicker to cross the busy road and so avoid the hole in the pavement altogether? Or will the time spent waiting for the traffic lights to change so that I can cross the road make me even later?

Panting, gulping in lungfuls of air, I decide to stay where I am, and I join the queue of people waiting to pass along the walkway. Others are coming from the opposite direction and we have to wait because there isn’t room for two lines of people, and they keep coming and we keep waiting.

Hurry! Hurry! Hurry! I scream silently, the words pulsing inside my head. Terrifying images of what might be happening at home if I don’t make it there on time flash through my mind, rewinding and replaying over and over again, ruthless, relentless.

Now panic sets in. I glance at my watch every couple of seconds, shifting from one foot to the other, praying for a break in the endless stream of people.

I should have crossed the road, I think, angry with myself, with the workmen who dug up the pavement and with the people who don’t let me pass. I should have crossed the road!

A mother with a baby in a buggy is the last person to negotiate her way carefully along the walkway towards us. The buggy is wide and the walkway is narrow and it seems to take her hours to reach the other end where we’re all waiting, while the baby sits upright in his seat like a cute, chubby little emperor, lord of all he surveys.

My throat closes up with fear. I’m late. Late!

The mother pushes the buggy out onto the wider pavement, and I skip round the people waiting in front of me and start running again. Alongside the hole, round the corner, down the next street.

To the traffic lights by the park – three minutes behind schedule.

Three minutes? Somewhere, somehow I have to make up lost time. The traffic lights are red when I arrive, the cars have stopped. With a sigh of relief, I skitter across the road and into the park. Sometimes, when I’ve been really late, I’ve taken a risk and crossed roads when the lights are green and cars are racing up and down. I’ve discovered that I can successfully dodge moving objects if I concentrate.

The park is a short cut and there aren’t many people around, so I pick up speed. It’s green and beautiful and flower-filled in the summer, but now, with winter rushing upon us, the trees are stark and black, surrounded by piles of dead and decaying leaves.

I’ve never been here with Mum, not even in the summertime. Mum collapses with panic, struggles to breathe and sobs at even the thought of leaving the house. She hasn’t been outside for seven years. The last time was just after I started school.

To the park exit – four and a half minutes. My lungs are bursting out of my chest, but I’ve shaved a minute off my best time. I must be getting fitter. I have three roads to cross now, and at each crossing all the traffic lights are on red and my hero, the green man, urges me to the other side before the cars set off again.

‘Three times in a row!’ I tell myself triumphantly. ‘That’s never happened before.’ And it’s saved me another two minutes. I’m back on schedule.

Life would be so much easier if I didn’t have to go to school at all, if I could just stay at home with my mother and look after her. I know Mum wishes I could too, but she won’t allow it. I worry about her endlessly when I’m away and I ring her at lunch time, every break time and between lessons if I can. She panics whenever she’s left on her own.

I never know what might have happened when I arrive home from school. Mum can only walk with sticks because her legs were injured in a car accident when I was very young, but even then she can’t get far without me to help her. Once she hobbled into the kitchen and tried to start cooking dinner and one of the pans caught fire. Sometimes she falls over and cuts her head or bruises herself and I find her lying on the floor in pain when I get back. She’s often convinced that someone has broken into the house while I’m away; she imagines that she hears noises and it makes her sick with fear. I worry, worry, worry about her every second I’m at school.

And Mum falls apart, piece by piece, if I’m not home on time. She can’t help it. Once I tripped over a broken bit of pavement and I scraped my knee and dropped my bag and everything fell out and I had to stuff it all back in – folders, books, pencil case, tissues – and then I had to run and run and run. I was nearly six minutes late that day.

Mum was crying hopelessly when I finally arrived home, and we fell into each other’s arms until we’d both calmed down. That was one of Mum’s Bad Days, when a cloud hangs over her so thick and black I can almost see it, separating her from me. I have nightmares about getting knocked down by a bus and being taken away to hospital and Mum not knowing where I am and panicking. I don’t know what would happen then. It frightens me. I try not to think about it.

The only times I don’t go to school is if Mum is having a Really Bad Day. When I skip school to stay home, I’m worried someone will notice, but it doesn’t happen all that often and so far nothing’s been said. No one at school knows about Mum, but my Year Group teacher, Miss Hardy, is starting to ask questions.

Will I see your mum at Parents’ Evening, Anjeela?

Is your mother coming to the Christmas concert?

Anjeela, would your mum be interested in helping out at the school car boot sale?

‘No, thank you, Miss Hardy,’ I reply with the bland, bright smile I’ve perfected over the years when anyone asks about Mum.

I think Miss Hardy is starting to get suspicious. But it’s none of her business. We’re not doing anything wrong. I can manage. I can cope. I can look after Mum on my own.

‘Do you mind this life, Anni?’ Mum asks me now and then. ‘It upsets me, the way you have to do everything. I know it isn’t fair to rely on you so much. But . . .’ Her voice always fades away, and she never finishes the sentence. Because she knows, like I do, that there’s no one else. There’ll never be anyone else.

‘I don’t mind, Mum,’ I always reply. And if it sounds like I’m telling the truth, then that’s because it is how I really feel. I look after Mum and care for her, whether she’s having a Good Day or a Bad Day, because she can’t do it herself, and that’s the way it’s been, ever since I can remember.

I’m close to our house and I’m bang on time. But when I turn the corner into Pride Street, a wide road lined with big white houses and leafy, spreading trees, it’s surprisingly full of people. Workmen are unloading steel barriers and yellow signs with black writing – THIS ROAD WILL BE CLOSED ON SATURDAY 8 NOVEMBER FROM 8 A.M. UNTIL 2 P.M. – from the back of a truck and there are litter-pickers and a road sweeper. Several police cars are parked by the kerb and passers-by are stopping to stare. I feel a jolt of nervousness. I don’t like police or anyone in authority. If they ever found out about me and Mum, I know they would split us up.

I wonder what’s going on, and then I remember hearing on TV that tomorrow the Prime Minister is visiting the new hospital not far from our house. This must be his route.

I’m so close to home I can see the red bricks of our tall chimneys just one street away in Silver Birch Lane. I feel a rush of pure relief that at least the house is still standing and isn’t on fire.

I won’t let all these people make me late now, not after I almost bust a lung to get here on time.

To avoid the nosy passers-by, I jump off the pavement and run along the gutter. Someone shouts out, ‘Hey, you!’ I don’t know if they’re yelling at me or not, but either way I ignore them.

To the bottom of Pride Street, then round the corner into Silver Birch Lane. The time is 4.03, leaving me two minutes to make it into the house. A perfect run.

The houses in Silver Birch Lane are even bigger and more expensive than those in Pride Street. They’re screened from view, surrounded by high fences and hedges, and I don’t know a single person who lives here. I’ve never met our next-door neighbours; I’ve seen them but we don’t speak. People keep themselves to themselves, and I too keep my own secrets close. There are things about me even Mum doesn’t know.

Our house, The Gables, is on the corner of the street. Like the others, it has a long winding drive with gates that are always kept locked, and it’s surrounded by high walls so no one can see much of the big front garden with its jungle of tangled undergrowth. The house is Victorian, red-brick and gothic with twisting corridors and sweeping staircases, like the setting for an old-fashioned story about star-crossed lovers, vampires and mysterious secret rooms. It has arched windows and two attics on the top floor, one enormous, one smaller.

At first glance, the house appears very grand. But look more closely and you’ll see that, as well as the overgrown garden, the roof tiles are mossy, cracked and broken, and in some cases missing altogether. Some of the windows are boarded up, and those that aren’t are hidden by thick, heavy curtains that don’t allow a chink of light in and are never drawn back. Ivy crawls across the red brickwork that in places is crumbling away into dust. It looks like no one lives here.

Despite it all, Mum clings to the house like a lifeline. She worries that if we tell anyone about our situation or ask for help, then we’ll be forced to leave.

‘The house is the only place where I feel safe,’ Mum says. She’ll stay until the house falls down around us, and I’ll stay there with her, right to the end. Looking at the state of the place, that time might not be very far off. My parents were wealthy before Dad died, but almost all the money is now long gone.

We never use the front door. I run down the side of the house, towards the gate into the back garden. The gate is always kept padlocked too, and the keys vanished long ago. Instead, I remove a loose board from the fence beside it so that I can slip through the gap into our huge back garden. The weeds and the grass are so high there could be a dead body lying amongst them and I wouldn’t even notice. I wedge the board back into place.

Thirty seconds to go.

Now I’m at the back door. Before I take the key from my pocket, I glance around to make sure no one’s watching. I always do this because Mum asked me to. She’s petrified of strangers, of intruders, of burglars breaking into the house and destroying what little peace of mind she has left.

The back door is old and warped and always sticks, and the large glass panel in the bottom is missing. I’ve had to board it up as best as I can. I push against the door with my shoulder, hard, and, protesting loudly, it finally creaks open.

Inside, I hang the key on the hook where it’s always kept, by the back stairs. Then I turn the corner and slip along the corridor, past the downstairs bathroom. I check the door. It’s locked. That’s how it should be. Everything is well.

Further along the corridor I stop at the next door. I don’t try the handle because I know it will be locked too. Instead, I tap crisply, three distinct knocks. Our sign.

‘Mum, it’s me,’ I call.

I hear Mum shuffling slowly across the room and then the sound of keys jangling as she unlocks the door. This is our routine every school day. Terrified of being alone, Mum barricades herself in her room, and she keeps the rest of the ground floor locked too. I leave lunch for her in her room every morning, and she only ever unlocks the door to go to the downstairs bathroom. I sometimes wonder how Mum would ever get out quickly if there was a fire. Another thing I try not to think about.

My relief that I’ve made it on time doesn’t last long as the door swings open. Inside the dimly lit room Mum is leaning on her sticks, and I can see from the shattering pain and anxiety etched on her face that this has turned into a Really Bad Day.

Mum shakes her head warningly at me.

‘Don’t make a noise,’ she whispers, her voice thick with terror. ‘There’s someone upstairs.’