She remembers sitting on the stairs outside their bedroom, listening to their muffled sobs as they wept for their lost son. She remarks, without self-pity, that despite her fondness for Jean, she herself remained dry-eyed. After the death of her mother, she says, she never cried again.

History records that in all the years that Le Coq Rouge was owned and run by the Montpellier family, it closed its doors only once: for a three-week period during 1925. Townspeople remember that Hélène, Jean-Michel, Mimi and Édith told nobody that they were going away but simply pulled down the shutters, locked the doors and disappeared, leaving an ‘en vacances’ sign on the door. This had led to no small degree of consternation within the little town, two letters of complaint to the local paper, and a good deal of extra custom for Le Bar Blanc. On the family’s return, when asked where she had been, Hélène had replied that they had travelled to Switzerland.

‘We consider the air there to be particularly good for Hélène’s health,’ Monsieur Montpellier said.

‘Oh, it certainly is,’ Hélène replied, with a small smile. ‘Most … restorative.’

Madame Louvier is recorded as remarking in her diary that it was one thing for hoteliers to disappear on a whim to foreign countries, without so much as a by-your-leave, but quite another for them to come back looking quite so pleased with themselves about having done so.

I never knew what happened to Sophie and Édouard. I know they were in Montreux up to 1926 but Hélène was the only one in regular contact and she died suddenly in 1934. After that my letters came back marked Return to Sender.

Édith Béthune and Liv have exchanged four letters, trading long-hidden information, filling in the gaps. Liv has begun writing a book about Sophie, having been approached by two publishers. It is, frankly, terrifying, but Paul asks her who is more qualified to write it.

The older woman’s handwriting is firm for someone of her advanced years, the copperplate evenly spaced and forward-slanting. Liv shifts closer to the bedside light to read it.

I wrote to a neighbour, who said she had heard Édouard had fallen ill, but could offer no evidence. Over the years other such communications led me to believe the worst; some remembered him becoming ill, some remembered Sophie as the one whose health failed. Someone said they had just disappeared. Mimi thought she heard her mother say they had gone somewhere warmer. I had moved so many times by then that Sophie would have had no way of contacting me herself.

I know what good sense would have me believe of two frail people whose bodies had been so punished by starvation and imprisonment. But I have always preferred to think that seven, eight years after the war, free of responsibility for anybody else, perhaps they finally felt safe enough to move on, and simply packed up and did so. I prefer to imagine that they were out there, perhaps in sunnier climes, as happy as they had been on our holiday, content in their own company.

Around her the bedroom is even emptier than usual, ready for her move the following week. She will stay in Paul’s little flat. She may get her own place, but neither of them seems to be in any hurry to pursue that conversation.

She gazes down at him sleeping beside her, still struck by how handsome he is, the shape of him, the simple joy of having him there. She thinks of something her father had said when he came for Christmas, seeking her out in the kitchen and drying dishes as she washed, while the others played noisy board games in the front room. She had looked up, struck by his uncharacteristic silence.

‘You know, I think David would have rather liked him.’ He didn’t look at her, but continued with his drying.

She wipes her eyes, as she does often when she thinks about this (she is giddily emotional at the moment), and turns back to the letter.

I am an old woman now, so it may not happen in my lifetime, but I believe that one day a whole series of paintings will emerge with unknown provenance, beautiful and strange, their colours unexpected and rich. They will feature a red-haired woman in the shade of a palm tree, or perhaps gazing out into a yellow sun, her face a little older, that hair perhaps streaked with grey, but her smile wide and her eyes full of love.

Liv looks up at the portrait opposite her bed, and the young Sophie gazes back at her, washed with the pale gold of the lamplight. She reads the letter a second time, studying the words, the spaces between them. She thinks back to Édith Béthune’s gaze: steady and knowing. And then she reads it again.

‘Hey.’ Paul rolls over sleepily towards her. He reaches out an arm and pulls her to him. His skin is warm, his breath sweet. ‘What you doing?’

‘Thinking.’

‘That sounds dangerous.’

Liv puts the letter down, and burrows under the duvet until she is facing him.

‘Paul.’

‘Liv.’

She smiles. She smiles every time she looks at him. And she takes a little breath. ‘You know how good you are at finding stuff …’