There were hundreds of Emily Burtons, right the way around the country. And dozens of them were about the right age. Miranda had travelled hundreds of miles. Not an Emily Josephine Burton, near Ludlow in Shropshire. Not Emily Rose Burton, just off the Royal Mile, in the heart of Edinburgh. Not an Emily Nugent, married – unhappily, from the quiet sag in her shoulders – to a choleric Nigel Burton, a chartered surveyor from Ipswich.

‘It’s taking up so much of your time,’ said Casey to Miranda, late one night.

‘But I’m the only one who saw her,’ said Miranda. ‘And Emily Burton was the only woman at Dr Greystone’s to fit our profile. It has to be her.’

And finally, Hessa had done one last search. ‘Emilia Burton-Smith,’ she announced to the room. ‘She’s an artist. Lives in Surrey, with her husband.’

Miranda studied the website Hessa had found. She worked in oils, Burton-Smith, huge splashing canvases, red on red. The photograph of the artist was small, though, black and white, blurred, half turned away from the camera.

‘It could be her,’ hesitated Miranda. ‘Maybe.’

‘She looks beautiful,’ said Hessa. ‘But that website is old, now.’

‘I should have asked one of you to wait outside the clinic,’ said Miranda. ‘So that at least you would have seen her too.’

‘I like her paintings,’ said Casey. ‘How long have they been living in Surrey?’

Hessa tapped at her computer.

‘They moved there a few years ago,’ said Hessa at last. ‘Out from Notting Hill.’

Waiting for the babies, Casey thought, that never came.

Hessa, tapping databases, found out more about Emilia and Dominic Burton-Smith. His family owned a swathe of Gloucestershire, it turned out. ‘Very low-profile,’ Hessa said. ‘But smart. They got married ten years ago. When she was twenty-one, and he was twenty-nine.’

‘Photographs?’ Miranda asked. ‘Of the wedding?’

‘No.’ Hessa sounded apologetic. ‘I can’t find them anywhere. There’s an address though.’

As Hessa read it out, Casey turned away, gouging at her desk with a pen.

‘I’ll go,’ said Miranda.

But when Miranda got to Surrey, an hour from the office, the house was still, empty.

‘They travel a lot.’ A neighbour ambled past, with a small terrier. ‘I keep an eye on it for them. I can let them know they missed you? Here, Choccy.’

Miranda smiled at the neighbour, and the terrier, and chatted on. And finally Casey and Miranda reached Bath, and the busy little square beside the Abbey. Now they watched, invisible from a small café, as the Burton-Smiths explored a little longer, and then turned away down the little street that ran next to the Roman Baths.

The man whispered something in Emily’s ear as they walked off, and she laughed up at him, stroking his face affectionately. And Casey and Miranda waited, and then they got up to follow.

As they made their way down the cold streets, Casey stopped sharply.