No, she couldn’t do it. Out of the question. Pity, though; it would have been the easiest thing in the world to say, at some point in the conversation, ‘I’ll spell my surname for you, since you’ll never have come across it before: Z-A-I-L-E-R.’ Surely Nikhil would then mention Liv, giving Charlie the opportunity to say, ‘But that’s extraordinary! She’s my sister.’

To which Nikhil would say … what? ‘Oh, really? My girlfriend Natalie and I have regular kinky orgies with Liv and her boyfriend Chris. Isn’t it a small world?’

It wasn’t sexual, Charlie was certain of that. She and her sister were different in many ways, but one thing they shared absolutely was a conviction that sex ought to mean two people in a room together and no more. They’d discussed it often over the years.

Whatever was going on between Liv and Gibbs and Nikhil and Natalie, it was something more … administrative than passionate. What Charlie had seen through the pub window the day she’d followed Liv to Cambridge was something being arranged, or an important issue under discussion. It was driving Charlie crazy that she couldn’t burst into the McElwee Winery and demand to know which, and what.

She opened her car door and smoked two cigarettes in quick succession reconsidering and rejecting the official police visit option three or four more times. It was infuriating that she could never risk her job because Simon was forever risking his – though he wouldn’t be fired now unless he burned down the nick or strangled a suspect. Proust, Superintendent Barrow, all the higher-ups – they knew they couldn’t afford to lose him. All of them would die rather than use the word genius, but they knew he was. Apart from in the pages of fiction, there was no detective in the country – perhaps in the world – as inspired or talented as Simon, no one else who could provide the kind of answers he came up with against the odds.

Charlie had to keep reminding herself that she, on the other hand, wasn’t special. It was a mistake to think that being Simon’s wife afforded her a certain amount of protection. She should have been doing the job she was paid to do today, not skiving off to solve her own pet mystery.

If only she could bring herself to confront Liv. That would be much easier to do now she had names to use. ‘I know about Nikhil and Natalie,’ she could say coldly. Or angrily, impatiently, with tears in her eyes – that might work better. ‘I know what’s going on, Liv. You should have told me the truth.’

Except Charlie didn’t want to find out that way. Her sister had chosen to deceive and manipulate her, and now she wanted to find out in spite of Liv, not with her help – not even by tricking a confession out of her.