‘Yet I keep hearing that they weren’t hippies,’ Proust said. ‘When in fact only a hippie or someone of that persuasion could hear the word “holistic” without gagging.’

‘I can promise you they weren’t hippies or anything like that – really,’ said Grace Woolston. ‘Angela McCabe was trying to write a screenplay and went on many creative writing courses – this one was in the sun, by a beach, so she thought, “Why not?” She had reservations about the holistic stuff, but she thought she could just ignore it.’

‘And what was Joshua Norbury’s excuse?’ Proust asked.

‘The crime we’re here to investigate is murder,’ Simon told him. ‘Not going on the kind of holiday you disapprove of. Norbury was young, gay and single and wanted to meet someone in the same situation – hopefully the love of his life. He’d been told by a mate that those holistic holidays were the place to go. Josh didn’t meet a romantic partner, but he did make a best friend for life: Angela McCabe.’

Simon stood up, walked over to the window and looked out at the blocks of flats opposite. He found it easier to speak in a group situation when he wasn’t looking at the people he was talking to. ‘Angela and her husband Russell owned a four-storey townhouse in Chiswick with a large outbuilding in their back garden, from which they ran their business: a small kung fu school. That’s a martial art. They didn’t make a fortune from it, but they didn’t need to. Both Angela and Russell had inherited an eye-watering amount of family money, so the school was more of a hobby than a necessity.’

‘Not fair, that,’ said Grace Woolston. ‘It was a proper business: professionally run and the classes were popular. Just because the McCabes had money doesn’t make them dilettantes.’

‘All right, fine,’ said Simon. ‘Crime scene: kitchen of the McCabe home. Same as the previous two victims: cups with remains of drinks found – one tea for Billy, coffee for Angela. Angela, like Rhian Douglas, was shot in her kitchen, but – key difference – Angela was the only one of the four not to be shot in the back of the head. She was shot here.’ Simon pointed to the spot between his eyebrows. ‘By her body, on the floor, was a biscuit tin and biscuits scattered everywhere. Theory: Billy was preparing to shoot her in the back of the head while she was facing the kitchen worktop, mugs, kettle, etcetera, but then she turned round, biscuit tin in hand, to offer him a biscuit – so he shot her face to face.’

‘I think Billy’s conflict-averse,’ said Kerensa Moore. ‘He likes – maybe even needs – everything to be friendly.’

‘Then he ought to consider not murdering people,’ said Proust.