‘We were called Sweet and Sour.’ Mum laughs, with a little shake in it. ‘I was the keyboard player – well, barely; I played piano, so we assumed that meant I’d be good at the keyboard, but actually I was terrible. And Dee could only play folk guitar and none of us had a note in our heads, so the whole thing was a disaster, but we had a wonderful time.’

Holly can’t stop looking. That girl in the photo isn’t one solid person, feet set solidly in one irrevocable life; that girl is an illusive firework-burst made of light reflecting off a million different possibilities. That girl isn’t a barrister, married to Frank Mackey, mother of one daughter and no more, a house in Dalkey, neutral colours and soft cashmere and Chanel No. 5. All of that is implicit in her, curled unimagined inside her bones; but so are hundreds of other latent lives, unchosen and easily vanished as whisks of light. A shiver knots in Holly’s spine, won’t shake loose.

She asks, ‘Where’s Miriam?’

‘I don’t know. It wasn’t the same without Dee, and during college we grew apart – I was terribly serious back then, very ambitious, always studying, and Miriam wanted to spend most of her time getting drunk and flirting, so before we knew it . . .’ Mum’s still gazing down at the photo. ‘Someone told me she got married and moved to Belfast, not long after college. That’s the last I heard of her.’

‘If you want,’ Holly says, ‘I’ll have a look for her on the internet. She’s probably on Facebook.’

‘Oh, darling,’ Mum says. ‘That’s very kind of you. But I don’t know . . .’ A sudden catch of her breath. ‘I don’t know if I could bear it. Can you understand that?’

‘I guess.’

Dad has a hand on Mum’s back, just lightly, between her shoulder blades. He says, ‘Need another glass of wine?’

‘Oh, God, no. Or maybe; I don’t know.’

Dad cups the back of her neck for a second and heads for the fridge.

‘So long ago,’ Mum says, touching the photo. The fizz is fading out of her voice, leaving it quiet and still. ‘I don’t know how it can possibly be so long ago.’

Holly moves back to her stool. She stirs bits of onion with the point of the knife.