‘Yes, this is crucial,’ said Kerensa Moore. ‘Sorry, DC Waterhouse – I know you’re keen to go on, but we need to state at every opportunity: this is Billy’s way of telling us that it’s about pairs of best friends, in case we were too slow to work it out. Rhian and Linzi got lines from the same poem. So did Angela and Joshua.’

‘The pairs thing was frustrating in the case of Angela,’ Simon went on. ‘The unmissable link to Linzi and Rhian via the little white book, I mean – because if that hadn’t been there, telling us it had to be the same killer, there’d have been an obvious suspect for Angela’s murder: thirty-six-year-old Gisela Bloor, receptionist at a car showroom in Ealing. Bloor has been semi-stalking Angela’s husband Russell for years, making a nuisance of herself in the guise of being a dedicated kung fu student. Russell McCabe wasn’t interested in her and nothing ever happened between them, but Gisela told everybody, including Angela and Russell, that she and Russell were destined to be together. It’s what the universe wants, apparently, she told anyone who would listen – and it would happen eventually whether Russell accepted his predetermined fate or not.’

‘Another unhinged hippy,’ said Proust.

‘She’s the most selfish individual I’ve ever met,’ said Neil Dunning. ‘She left her husband and son to pursue Russell, to be available for when he finally saw the light, which he insists he never will. Now that Angela’s dead, he seems even more determined. Can’t say I blame him. Gisela’d make anyone’s skin crawl, but she’s not a murderer. She was stroking shiny hatchbacks in the showroom the day Angela was murdered. No payments to hitmen, either – not that we can find any trace of. Also, if you’d met her, you’d know she’d never put herself out to find a gun and learn how to use it – the universe is expected to do all the work and bring her what she wants without her having to make an effort.’

‘Gisela could be Billy,’ Simon insisted. ‘Somehow, some way – even if it looks, for the moment, like she couldn’t.’

‘Then so could Sondra Halliday,’ said James Wing. ‘Just as likely, given her obsession with the Billy killings – and we don’t know she has alibis.’

‘What’s Gisela’s motive for killing Rhian and Linzi?’ asked Neil Dunning. ‘Big fat nothing.’