Everyone was silent as I announced my theory about Frederick.

‘He’s the Snake. He has to be.’

‘He couldn’t just be a shit dad?’ asked Cameron.

‘A sociopath is the most likely person to be a traitor. All about the money. No feelings of loyalty. No remorse at getting colleagues killed.’

I thought of him sitting there coldly as his own daughter writhed in pain at his feet.

Hattie’s phone rang. He looked down at it. ‘It’s the lab.’ He answered. ‘What have you found?’ He nodded silently. ‘Thanks.’ He hung up and looked round at us. ‘Lex was right. Both the EpiPens contained a lethal dose of arsenic.’

Jake whistled slowly. ‘Good save, Lex.’

‘It was the clearest move – the Coyote wouldn’t even need to be in the room when Peng died. It would be the perfect cover. He just needed to spike the food with nuts and once Peng suffered an adverse reaction, one of her own team would unwittingly kill her with a spiked EpiPen. They would be the ones under suspicion. It would be chaos. Impossible to pull apart.’

‘How the hell did the Snake – Frederick, or whoever – get to all the EpiPens?’ said Jake. ‘They must have someone inside the delegation.’

I thought it through.

‘We did this.’

Everyone turned to look at me.

‘We got Frederick access and a reason to be near the delegation – he was one of us. I was updating him on what we’d learned, on the delegation’s movements. Everything. He could’ve swapped the EpiPens over at the Natural History Museum event or Cherwell Castle.’ I paused. ‘If I’m right, it explains why he came to us with Tenebris. He needed us to have direct access to Peng. The Snake never had a contact within the delegation. He didn’t need one. We did all the dirty work, giving him all the information he needed to make the hit.’

Hattie leaned back in his chair; his fingers formed a bridge.

‘It sounds like we’ve been used.’

Jake shrugged. ‘How do we know Peppa isn’t also a Snake? That they’ve been working together? This nanny thing might be true but there’s still the dry-cleaning link to the Embassy.’

Geraint shook his head. ‘That’s looking like a dead end now. Peppa has booked a Rentokil visit for next week. Her house has a moth infestation, apparently. It explains the sudden increase in dry-cleaning visits. Only way to kill the sods and save your cashmere.’

‘And I finally tracked down the dry cleaner’s sister,’ added Pixie. ‘The reason we’ve been having trouble locating her is because she’s on maternity leave. She hasn’t set foot in the Embassy in the last two months.’

I took this in. ‘I think Frederick is the Coyote and the Snake. He was the one selling information that sabotaged those previous Six missions. And he just tried to assassinate Peng.’