‘But that tent, it was right on the shoreline. Everything’s moved. They won’t be able to find too much out from the exact placement, I’m sure of it.’

I don’t answer. I feel sick to my stomach.

Because although there’s something comforting about her certainty, although I want to believe her, I’m not so sure she’s right. It’s a long time since I’ve done criminal work, and I know more from watching Cold Case than I can remember from the cases we studied at uni, but I’m pretty sure they have forensic specialists who can tell exactly how an object might have moved and shifted through the sands over the years.

‘Let’s not talk about it here,’ I mutter, and Thea nods, and forces a smile. ‘Tell me about work,’ I say at last. She shrugs.

‘What’s to tell? It’s good, I guess.’

‘You’re back in London?’

She nods.

‘I had a pretty fun stint last year on one of the big cruise ships. And Monte Carlo was excellent. But I wanted …’ She stops, looks out of the window. ‘I don’t know, Isa. I’ve been wandering around for so long, Salten was probably the longest I ever stayed at a school. I felt it was probably time to put down some roots.’

I shake my head, think of my own plodding progression through school, uni, Bar exams, the Civil Service, and life in London with Owen. We are the exact opposite, she and I. I am limpet-like in my tenacity. I found my job, and I stuck to it. I found Owen, and I stuck to him too. Salten House, for me, was this dizzyingly brief interlude. And yet both of us are equally defined by what happened there. We’re just coping with it in very different ways. Thea, restlessly running from the shadow of the past. Me, clinging on to the things that anchor me to safety.

I look at her thinness, at the shadows beneath her cheekbones, and then down at myself, Freya clamped to my body like a human shield, and for the first time I wonder – am I really dealing with this any better than her, or have I simply worked harder to forget?

I am still wondering, when there is a croaking cry at my breast, and a wriggling inside the sling, and I realise that Freya is waking up.

‘Shhh …’ Her cries are getting louder and more cranky as I pull her out of the swathes of material, her fat little cheeks flushed and annoyed as she gears up for a full-on tantrum. ‘Shhh …’

I pull open my top and put her to my breast, and for a minute there is silence, beautiful silence. Then, without warning, we go into a tunnel, and the train plunges into blackness. Freya tips her head back in wonder, her eyes dark and wide at the sudden change, exposing a wet flash of nipple to the carriage before I can grab for a muslin.

‘Sorry,’ I say to Thea, as we pass, blinking, back into the sunshine and I push Freya’s head back into place. ‘I think at this point half of north London has seen my tits, but you’ve had more than your fair share this week.’

‘It doesn’t bother me,’ Thea says with a shrug. ‘God knows, I’ve seen it all before.’

I can’t help but laugh as I lean back, Freya warm and heavy in my arms, and as the train enters another tunnel and emerges again into the searing sunshine, I think back, back to that first time we met, to Thea, rolling her stockings up her long, slim legs, the flash of thighs and me blushing. It seems like a lifetime ago. And yet, as Thea stretches out her legs across the gap between the seats, gives me a lazy wink and closes her eyes, it could be yesterday.

Rule Four

Never Lie to Each Other

‘ISA?’

Owen’s call as he opens the front door is low, cautious, but I don’t reply at first. I’m putting Freya down in her crib in our room, and I don’t want to wake her. It’s right at the tricky stage where she might sleep … or she might go for another hour of crankiness and fussing. She has been hard to get down tonight, unsettled by yet another change of scenery.

‘Isa?’ he says again, appearing at the door of our bedroom and when he sees me his face breaks into a huge grin, and he pulls off his shoes and tiptoes across the boards even as I frantically put my finger to my lips, signalling quiet.

He comes to stand beside me, his arm around my waist, and together we look down at this creature we’ve made.

‘Hello, sweetie,’ he whispers, but not to me, to Freya. ‘Hello, honeybunch. I’ve missed you.’

‘We missed you too,’ I whisper back, and he kisses my cheek and draws me out into the hallway, part shutting the door behind us.

‘I wasn’t expecting you for ages,’ he says as we go downstairs to where baked potatoes are cooking in the oven. ‘You made it sound like you’d be gone for days. It’s only Wednesday – what happened? Did things not work out with Kate?’

‘Things were fine,’ I say. I turn my back, ostensibly taking the potatoes out of the oven, but really so I don’t have to see his face as I lie to him. ‘It was lovely, actually. Fatima and Thea were there too.’

‘Then why are you back so soon? You didn’t have to hurry back for me, you know that. I mean, don’t get me wrong, I missed you. But I didn’t get around to half the stuff I meant to do. The nursery’s still a wreck.’

‘That doesn’t matter,’ I say, straightening up. My cheeks are flushed with the heat from the oven. Baked potatoes is a silly choice for such a hot day, but it was all we had in the fridge. I put them on a board on the countertop and slice the sides open, watching the steam billow out. ‘You know that.’

‘It matters to me.’ He puts his arms around me, his day-old beard rough against my cheek, his lips questing for my ear, the side of my neck. ‘I want you back, all to myself.’

I let him kiss me, but I don’t say what I’m thinking, which is that if that’s what he wants, he will never be happy. Because I will never be his alone. I will always be nine-tenths Freya’s, and what little there is left over, I need for myself, and for Fatima, Thea and Kate.

‘I missed you,’ I say instead. ‘Freya missed you too.’

‘I missed you both,’ he says, his voice muffled in my collarbone. ‘I wanted to call, but I thought you’d be having such a good time …’

I feel a twinge of guilt as he says the words, as I realise that I barely thought about calling him. I texted, to say we’d arrived safely. That was it. Thank God he didn’t ring – I try to imagine my phone going – when? During that long, painful dinner? During the fight with Luc? On that first night as we all gathered, full of fear about what we were about to hear?

It’s impossible.

‘I’m sorry I didn’t phone too,’ I say at last, disengaging myself and turning off the oven. ‘I meant to – it’s just, you know what it’s like with Freya. She’s so whiny in the evenings, especially in a strange place.’

‘So … what was the occasion?’ Owen asks. He begins to get salad out of the drawer, sniffing the limp lettuce and picking off the floppy outer leaves. ‘I mean, it’s a funny time to get together – midweek I mean. I can see it doesn’t make any difference to you and Kate. But doesn’t Fatima work?’

‘Yes. There was a dinner – an alumnae dinner at Salten House. They held it on a Tuesday, I don’t know why. I suppose because the school’s empty then.’

‘You didn’t tell me about that.’ He starts to chop tomatoes, slice by slice, the pale juice bleeding across the plates. I shrug.

‘I didn’t know. Kate bought the tickets. It was a surprise.’

‘Well … I’ve got to say, I’m surprised too,’ Owen says at length.

‘Why?’

‘You always said you’d never go back. To that school, I mean. Why now?’

Why now. Why now. Fuck. Why now?

It’s a perfectly reasonable question. And I can’t think of an answer.

‘I don’t know,’ I say at last, testily. I push his plate towards him. ‘OK? I don’t know. It was Kate’s idea and I went along with it. Can we stop with the third degree? I’m tired, and I didn’t sleep very well last night.’

‘Hey.’ Owen’s eyes open wide, he holds up his hands. He’s trying not to show it, but there is hurt in his face, and I want to bite my own tongue. ‘Sure, blimey, sorry. I was just trying to make conversation.’