‘My dress is wrong, isn’t it?’ she whispered at me. ‘I have made huge mistake.’

She had seen it. In the sea of bodies it looked somehow too bright, less avant-garde than vulgar. ‘What am I going to do? Is disaster. I must change.’

I tried to calculate whether she could reasonably make it home and back. Even without traffic she would be gone an hour. And there was always the risk she might not come back …

‘No! It’s not a disaster. Not at all. It’s just about …’ I paused. ‘You know, a dress like that, you have to style it out.’

‘What?’

‘Own it. Hold your head up. Like you couldn’t give a crap.’

She stared at me.

‘A friend once taught me this. The man I used to work for. He told me to wear my stripy legs with pride.’

‘Your what?’

‘He … Well, he was telling me it was okay to be different from everyone else. Agnes, you look about a hundred times better than any of the other women here. You’re gorgeous. And the dress is striking. So just let it be a giant finger to them. You know? I’ll wear what I like.’

She was watching me intently. ‘You think so?’

‘Oh, yes.’

She took a deep breath. ‘You’re right. I will be giant finger.’ She straightened her shoulders. ‘And no men care what dress you wear anyway, yes?’

‘Not one.’

She smiled, gave me a knowing look. ‘They just care what is underneath.’

‘That’s quite a dress, ma’am,’ said Joshua, appearing at my side. He handed us each a slim glass. ‘Champagne. The only yellow drink was Chartreuse and it made me feel kind of queasy just looking at it.’

‘Thank you.’ I took a glass.

He held out his hand to Agnes. ‘Joshua William Ryan the Third.’

‘You really have to have made up that name.’

They both turned to look at me.

‘Nobody outside soap operas can actually be called that,’ I said, and then realised I had meant to think it rather than say it aloud.

‘Okay. Well. You can call me Josh,’ he said equably.

‘Louisa Clark,’ I said, then added, ‘The First.’

His eyes narrowed just a little.

‘Mrs Leonard Gopnik. The Second,’ said Agnes. ‘But then you probably knew that.’

‘I did indeed. You are the talk of the town.’ His words could have landed hard, but he said it with warmth. I watched Agnes’s shoulders relax a little.

Josh, he told us, was there with his aunt as her husband was travelling and she hadn’t wanted to attend alone. He worked for a securities firm, talking to money managers and hedge funds about how best to manage risk. He specialized, he said, in corporate equity and debt.

‘I don’t have a clue what any of that means,’ I said.

‘Most days I don’t either.’

He was being charming, of course. But suddenly the room felt a little less chilly. He was from Back Bay Boston, had just moved to what he described as a rabbit-hutch apartment in SoHo, and had put on two kilos since arriving in New York because the restaurants downtown were so good. He said a lot more, but I couldn’t tell you what because I couldn’t stop staring at him.

‘And how about you, Miss Louisa Clark the First? What do you do?’

‘I –’

‘Louisa is a friend of mine. Just visiting from England.’

‘And how are you finding New York?’

‘I love it,’ I said. ‘I don’t think my head has stopped spinning.’

‘And the Yellow Ball is one of your first social engagements. Well, Mrs Leonard Gopnik the Second, you don’t do things small.’

The evening was flying by, eased by a second glass of champagne. At dinner, I was placed between Agnes and a man who failed to give me his name and spoke to me only once, asking my breasts who they knew, then turning his back when it became clear that the answer was not very many people at all. I watched what Agnes drank, on Mr Gopnik’s orders, and when I caught him looking at me I switched her full glass for my near-empty one, feeling relief when his subtle smile signalled approval. Agnes talked too loudly to the man on her right, her laugh a little too high, her gestures brittle and fluttery. I watched the other women at the table, all of them forty and above, and saw the way they looked at her, their eyes sliding heavily towards each other, as if to confirm some dark opinion expressed in private. It was horrible.

Mr Gopnik could not reach her from his position across the table, but I saw his eyes flickering towards her frequently, even as he smiled and shook hands and appeared, on the surface, to be the most relaxed man on the planet.

‘Where is she?’

I leant in to hear Agnes more clearly.

‘Leonard’s ex-wife. Where is she? You have to find out, Louisa. I can’t relax until I know. I can feel her.’

Big Purple. ‘I’ll check the place settings,’ I said, and excused myself from the table.

I stood at the huge printed stand at the entrance to the dining room. There were around eight hundred closely printed names and I didn’t know if the first Mrs Gopnik even went by Gopnik anymore. I swore under my breath just as Josh appeared behind me.

‘Lost someone?’

I lowered my voice. ‘I need to find out where the first Mrs Gopnik is seated. Would you happen to know if she goes by her old name? Agnes would like … to have an idea where she is.’

He frowned.

‘She’s a little stressed,’ I added.

‘No idea, I’m afraid. But my aunt might. She knows everyone. Stay right here.’ He touched my bare shoulder lightly and strode off into the dining room, while I tried to rearrange my facial expression into that of someone who was scanning the board to confirm the presence of half a dozen close friends, not someone whose skin had just coloured an unexpected shade of pink.

He was back within a minute.

‘She’s still Gopnik,’ he said. ‘Aunt Nancy thinks she might have seen her over by the auction table.’ He ran a manicured finger down the list of names. ‘There. Table 144. I walked past to check and there’s a woman who fits her description. Fifty-something, dark hair, shooting poison darts from a Chanel evening bag? They’ve put her about as far away from Agnes as they could.’

‘Oh, thank God,’ I said. ‘She’ll be so relieved.’

‘They can be pretty scary, these New York matrons,’ he said. ‘I don’t blame Agnes for wanting to watch her back. Is English society this cut-throat?’

‘English society? Oh, I don’t – I’m not very big on society events,’ I said.

‘Me either. To be honest, I’m so worn out after work that most days it’s all I can do to pick up a takeout menu. What is it you do, Louisa?’

‘Um …’ I glanced abruptly at my phone. ‘Oh, gosh. I have to get back to Agnes.’

‘Will I see you before you go? Which table are you at?’

‘Thirty-two,’ I said, before I could think about all the reasons I shouldn’t.

‘Then I’ll see you later.’ I was briefly transfixed by Josh’s smile. ‘I meant to say, by the way, you look beautiful.’ He leant forward, and lowered his voice so that it rumbled a little by my ear. ‘I actually prefer your dress to your friend’s. Did you take a picture yet?’