One mistake, one bad judgement, can change a life forever.

Yvonne Carmichael seemed to be a woman who had everything. A successful career; she was a scientist, a geneticist, and she had climbed to the very top of her profession. A long and stable marriage, to a good man. Two children – a boy and a girl – both grown up and independent. A lovely home …

But, for all that, there was something missing. She wanted someone to look at her – not as wife, not as a mother, not as a professional – but as an interesting, attractive woman.

Maybe the man she met, when she was giving evidence to a Select Committee at the Houses of Parliament saw that. And maybe she saw something in him. Or maybe it was a classic coup de foudre. Whatever it was, they fell into an intense, physical affair.

They were careful to keep it secret – she loved her husband, he didn’t want to hurt his wife – but they were both caught up, they behaved recklessly. And there were terrible, terrible consequences.

Yvonne didn’t want to tell her husband – she couldn’t without telling him about her affair – and she tried to cope alone. But she couldn’t cope, and she chose to talk to her lover. And that set off a chain of events that would end with them both on trial at the Old Bailey.

Still Yvonne didn’t want to tell her husband, didn’t want to hurt her family …

That was were the story began – with Yvonne in the witness box, being asked about Apple Tree Yard, and knowing when she hears those words that her world is about to crumble. It’s a dramatic, attention grabbing opening, and I so wanted to know what had happened, what had led her there.

I found out as Yvonne told her story, a mixture of recollections and letters to her lover that she would never send. At first I questioned the way the story was told, and I decided that a more straightforward confessional style would have been more effective, but as the story progressed I realised that I was wrong and the author was right: the style she chose allowed her to strike the perfect balance between telling the story and exploring Yvonne’s emotions, and the reasons why she did the things she did.

I didn’t like her, but I didn’t dislike her either. The affair was madness, but I could see what made her susceptible, and though I didn’t understand many of her decisions I did appreciate that she wanted to protect her family, but the more I learned the more I understood. Crucially, I believed in her. Psychologically, her story worked.

There was some very clever and well thought out writing going on to make all of that work, to keep the story compelling, and to keep a degree of suspense to the very end.

It was only at the very end, when all of the drama was over that the story maybe lost a little credibility, by leaving no space for the reactions of Yvonne’s wife and closest friend. The resolution was a little too simple for the story that had gone before.

It was a story of the consequence of deceit, and of the way those consequences can spiral. It was perfectly observed, it was clearly carefully researched, and it made some telling points about 21st century society. But that never overwhelmed the story of one woman, who made a mistake, and had to deal with terrible consequences.

A credible, believable story, told with real understanding …