‘Trust?’ screamed Marnie, beside herself with hurt, misery and mortification. ‘Don’t you dare to talk to me about trust any more! Very convenient – play on my insecurities, read me pious lectures about trusting people more, then sleep with someone else the minute my back’s turned! Obviously you wondered if you’d backed the wrong one between Louisa and me. I didn’t come up to expectations so you thought you’d try the other option! You two-timing bastard! I thought you were different and you know what? I even told my father I thought I’d found my soulmate!’ She laughed hysterically. ‘Go to hell, Christopher Piper,’ she said. ‘I never want to see you or hear from you again . . .’

Christopher, white with anger, slammed the telephone down.

Later, he contemplated ringing Louisa to ask if he could e-mail Marnie with an account of what had really happened, but a genuine conviction that Louisa had more than enough to cope with without being embroiled in lovers’ quarrels – particularly this one – plus a less worthy sense of fury at Marnie for not giving him the benefit of her very obvious and unflattering doubt, stopped him from doing so.

On the other side of the Atlantic, Marnie seethed and bubbled with resentment, not only with Christopher, which was so painful she felt physically ill, but also against Louisa – Louisa, to whom she had offered her friendship; Louisa who knew very well the depth of her feelings for Christopher but to whom, in Marnie’s view in her present wrought-up state, cock-teasing was just a light-hearted parlour game.

Her father had left early on another business trip without seeing her, though he would be back the next morning. Her stepmother Toni watched her uneasily, made excuses to check on her, and wondered if she should alert her husband to the fact that Marnie seemed alarmingly disturbed about something.

It was twenty-four hours before Marnie rang Louisa – at which point she felt that if she didn’t give vent to her sense of outrage and betrayal she thought she might, literally, burst.

Louisa was sitting in the garden with Adam. The blackbird still sang from the roof of the next-door house; the laburnum cascaded with yellow streamers as it always did at the beginning of June; the background hum of London’s rush hour traffic sounded the same as ever, but for Louisa everything had changed. When her mobile rang, she answered it automatically.

‘Oh, hi there, Marnie,’ she said, and thought with surprise that Christopher must have told Marnie about her even though she’d asked him not to mention it to anyone, but that it really didn’t matter. What difference could it make now? Everyone would know soon enough. ‘Christopher told you then?’ she queried.

‘No,’ said Marnie scornfully. ‘He didn’t need to. But I know all the same. How could you, Louisa?’

‘What are you talking about?’