UPSTAIRS I ALMOST bump into Fatima on the landing, coming out of her room, Kate’s old room.

‘Sorry,’ I say breathlessly. ‘Freya’s …’

She stands back, letting me pass, and I sprint into the room at the end of the corridor, where Kate has set up the bentwood cradle that once held her, as a baby.

It’s a beautiful room – the best perhaps, except maybe the one Kate herself now occupies, a bedroom and studio combined, which is the entire top floor of the mill and used to be her father’s.

When I pick Freya up she is hot and sticky, and I peel her out of her sleeping bag, realising how warm it is here. As I’m shushing her over my shoulder, I hear a noise behind me and turn to see Fatima in the doorway, looking wonderingly around, and I realise what I failed to notice as I hurried past her on the landing: she’s still fully dressed.

‘I thought you were going to bed?’

She shakes her head.

‘I was praying.’ Her voice is low and hushed, trying not to spook Freya. ‘It’s so weird, Isa. Seeing you here, in his room.’

‘I know,’ I say. I settle myself on the wicker chair while Fatima steps over the threshold and takes in our surroundings: the low slanting windows, the polished dark wood floor, the leaf skeletons strung from the beams, shivering in the warm breeze from the open window. Kate has taken away most of Luc’s possessions, his music posters, the pile of unwashed clothes behind the door, the acoustic guitar propped up against the windowsill, the ancient seventies turntable that used to rest on the floor by the bed. But it is still haunted by his presence, and I can’t think of it as anything but Luc’s room, even though Kate called it the back bedroom when she took me up.

‘Did you keep in touch?’ Fatima asks. I shake my head.

‘No, you?’

‘No.’ She sits on the edge of the bed. ‘But you must have thought about him, right?’

I don’t answer for a minute; I take a moment, rearrange the muslin next to Freya’s cheek.

‘A bit,’ I say at last. ‘Now and then.’

But that’s a lie – and worse, it’s a lie to Fatima. That was the most important rule of the Lying Game. Lie to everyone else, yes. But to each other – never.

I think of all the lies I have repeated and repeated over the years, until they became so engrained they felt like the truth: I left because I wanted a change. I don’t know what happened to him, he just disappeared. I did nothing wrong.

Fatima is silent, but her bird-bright eyes are steady on me, and I let my hand drop from where I have been fiddling with my hair. When you watch people lying as often as we have, you get to know each other’s tells. Thea bites her nails. Fatima avoids eye contact. Kate goes still and remote and unreachable. And I … I fret at my hair, twining it into knots around my fingers, weaving a web as tangled as our falsehoods, without even noticing what I’m doing.

I worked so hard to overcome it, back then. And now I can see from Fatima’s sympathetic smile that my old quirk has betrayed me again.

‘That’s not true,’ I admit. ‘I did think about him … a lot. Did you?’

She nods.

‘Of course.’

There is silence, and I know we are both thinking about him … about his hands, long and narrow, with strong fingers that ran across the strings of the guitar, first slow as a lover, then faster than you could see. About his eyes, changeable as a tiger’s, and the way they flickered from copper-coloured in the sunshine to golden brown in the shadows. His face is etched into my memory, and now, I see him, so clearly that it’s almost as if he’s standing in front of me – the jutting Roman nose that made his profile so distinctive, the broad expressive mouth, the sweep of his brows and the way they winged upwards slightly at the edges, giving him the look of someone always just about to frown.

I sigh, and Freya stirs in her light slumber.

‘Do you want me to go?’ Fatima says quietly. ‘If I’m disturbing her …’

‘No, stay,’ I say. Freya’s eyes are drifting shut and then snapping open, and her limbs are becoming loose and heavy, and I know she is nearly back to sleep.

Freya is lolling now, and I lay her gently into the cradle.

Just in time, for below I hear the sound of footsteps, and a crash as a door is flung open, and Thea’s voice, ringing through the house above Shadow’s barking.

‘Honeys, I’m home!’

Freya startles, flinging out her arms, starfish-wise, but I put a hand on her chest, and her eyes drift shut, and then I follow Fatima out of Luc’s room, and down the stairs to where Thea is waiting.

LOOKING BACK AT Salten House, the thing that I remember most is the contrasts. The searing brightness that came off the sea on a sunny winter’s day, and the midnight black of a country night – deeper than any London dark. The quiet concentration of the art rooms, and the shrieking cacophony of the buttery, with three hundred hungry girls waiting to be fed. And, most of all, the intensity of the friendships that sprang up after only a few weeks in that hothouse atmosphere … and the enmities that went with that.

It was the noise that struck me most, that first night. Fatima and I were unpacking when the bell went for supper, moving around the room in a silence that was already companionable and easy. When the bell shrieked out and we tumbled hastily into the corridor, the wall of sound that met us was like nothing I had heard at my day school – and it only intensified when we walked into the buttery. Lunch had been busy enough, but girls had been arriving all day, and now the hall was rammed, the din of three hundred high-pitched voices enough to make your eardrums bleed.

Fatima and I were standing uncertainly, looking for a space to sit as girls pushed purposefully past us on all sides, heading for their own particular friends, when I saw Thea and Kate at the end of one of the long polished wood tables. They were facing each other, and there was a spare place beside each of them. I nodded at Fatima and we began to make our way over – but then another girl cut in front of us, and I realised she was aiming there too. There would not be enough space for all of us.

‘You take it,’ I said to Fatima, trying to sound as if I didn’t mind. ‘I’m happy going on another table.’

‘Don’t be silly.’ Fatima gave me a friendly shove. ‘I’m not abandoning you! There’s got to be two seats together somewhere.’

But she didn’t move. There was something about the way the other girl was walking towards Kate and Thea that didn’t seem quite right – there was a purpose to it, a hostility that I couldn’t quite pin down.

‘Looking for a seat?’ Thea said sweetly as the girl reached her. I’d later come to know her as Helen Fitzpatrick, and she was cheerful and gossipy, but now she laughed, disbelieving and bitter.

‘Thanks, but I’d rather sit by the toilets. Why the hell did you tell me Miss Weatherby was pregnant? I sent her a congratulations card, and she went completely mental. I’ve been gated for six weeks.’

Thea said nothing, but I could see she was trying not to laugh, and Kate, who was sitting with her back to Helen, mouthed ten points, and held up her fingers to Thea, grinning.

‘Well?’ Helen demanded.

‘My mistake. I must have misheard.’

‘Don’t bullshit me! You’re a filthy liar.’

‘It was a joke,’ Thea said. ‘I never told you it was definite – I said I’d heard on the grapevine. Next time, check your facts.’

‘I’ll give you facts. I heard some facts about your last school, Thea. I met a girl from there at tennis camp. She said you’re not right in the head and they had to expel you. Well, they had the right idea, if you ask me. The sooner they chuck you out of here the better as far as I’m concerned.’

Kate stood up at that and swung round to face Helen. Her face was quite changed from the mischievous, friendly expression I’d seen on the train. It was full of a cold, hard anger that scared me a little.

‘You know what your problem is?’ She leaned forward, so that Helen took a step back, almost involuntarily. ‘You spend far too much time listening to rumours. If you stopped believing every nasty bit of gossip floating around, you wouldn’t have got grounded.’