Neither Rosalind or Posy needed any context to join in the conversation. Caro liked that. It made her feel they were on the same wavelength, inhabiting the same character, even. Her wife, Annie, needed context clues sometimes, to catch up with the conversations Caro had been having in her head before she asked Annie to join in.

‘First … are we sure it’s murder?’ Posy asked.

‘No,’ Caro admitted. ‘We can’t be sure until the post mortem comes back. But that could take days. And if it is murder …’

‘We have to start asking questions now,’ Posy finished with a nod. ‘Okay. How?’

‘We need to go over what we observed last night,’ Rosalind said. ‘Who sat where, when. Who left the room. That sort of thing. Between us, we should be able to recreate what happened last night, and figure out who murdered Marcus, and when.’

‘It’s simple deductive reasoning,’ Caro said, cheerfully. ‘Like Dahlia always does.’

‘We’re assuming the poison was in the coffee, I take it?’ Posy asked, grabbing another mini pastry. ‘Only, I checked last night, and the poison used in the book was aconite, which is apparently very fast acting in a large enough quantity. But the murderer could have used something else, something that would take longer to take effect, and added it to one of the earlier courses.’

Aconite. Of course it was. Caro knew that. Interesting that Posy had the book to go and check, though. ‘Well, if it was earlier, it could have been anyone. Everyone sat next to him at one point or another – even us. But if it was the coffee …’

She squinted in the sunlight, trying to remember who’d been next to him at the end.

‘If it was the coffee, it had to be someone sitting reasonably close to him at that time, or someone who stopped by to talk to him,’ Rosalind summarised. ‘Someone who could drop it in his cup, since no one else’s coffee was poisoned.’

‘Exactly. Which narrows it down to Ashok and Felicity on one side, and Posy and Harry on the other.’

‘And Heather,’ Posy put in. ‘She stopped by to talk to Marcus about something or other around then, I’m almost sure.’

‘Five people,’ Caro mused. ‘Four, if we discount Posy. But only if it was in the coffee.’

‘We need to know if it really was aconite that killed him.’ Posy pulled a face. ‘How do we do that without a post mortem report?’

‘Or how do we steal a post mortem report?’ Rosalind asked and shook her head. ‘Alternatively, we could leave this to the police.’

There wasn’t a chance of Caro doing that. ‘We need to know more about the poison. How it works, how it affects the body, that sort of thing. Aconite comes from a plant, doesn’t it? Monkshood, I think. I’m no gardener, but there might well be some here.’