‘You believe e-readers are evil, don’t you, Isobel? Why are bookshops closing all over the country? Because of e-books – people don’t need the paper versions any more. And so Rudolphy’s had to close, and your mother died. And you happened to know, probably because Linzi, Josh and Marion were all regular customers of yours, and Rudolphy’s would have prided itself on chatting to its regulars and knowing them really well, I’m sure – you knew the full stories behind those three unwanted e-readers, didn’t you? You knew the three givers – Rhian, Marion and Angela – weren’t keen themselves, and you knew the three recipients – Linzi, Kim, Josh – had no time for e-books and preferred to read their paper equivalents. None of the six was seduced or impressed, yet they helped to promote what you saw as an evil thing.’

‘The evil machine,’ Isobel corrected him.

‘You decided to punish them, didn’t you?’

‘No. Not punishment. Just … something had to be done. To prove someone cared, that this mattered to somebody. When historians look back in hundreds of years’ time, I want them to be able to say: “One woman cared. One woman, Isobel Sturridge, really cared. And she did something about it.” The people who … who died … they had no excuse. There were no mitigating circumstances, so …’ She stopped and pressed her lips together.

‘So you murdered them,’ said Simon. ‘And now I’m the brilliant detective delivering the ingenious solution in front of a crowd. That pleases you, doesn’t it? Because you love books – proper books. This is a crime story, isn’t it, that we’re all in? And you want and need it to be a proper one. That’s why it mattered so much to you to have a denouement – here, with us all gathered together, like in a detective story, and me explaining everything.’

‘Yes,’ Isobel said fiercely.

‘That’s why you wanted Kim and Drew here.’

‘Yes, because otherwise it would have been unbalanced. It’s still unbalanced, even with them here. There are supposed to be more people who aren’t the police than who are – you need plenty of suspects.’ Isobel stared at Simon, her mouth twitching. ‘There were lots of others you could have invited too: the families of Linzi, Rhian, Angela and Josh would have been a good start. Josh!’ she spat, suddenly. ‘What was wrong with him? He hated his evil machine, but would he throw it away? No, he wouldn’t – because it was a present from Angela, who told me herself when she was in the shop once, when she was visiting Josh: she loathed the whole idea of e-books herself – much preferred real books. Then why buy a Kindle as a present for your best friend? Angela said, “I’d run out of ideas of things to get him. He had everything else.” I mean … surely you can see that sort of attitude is unconscionable?’