During the day, if I wasn’t in the lab or studying, or out, it was my job to listen for the bell and answer the front door when it rang. This happened so infrequently that the first time it occurred it took me a minute to work out what the noise was.

It turned out to be Beverley Brook in an electric-blue quilted jacket with the hood up.

‘You took your time,’ she said. ‘It’s freezing out here.’

I said she should come in but she looked shifty and said she couldn’t.

‘Mum says I’m not to, she says that it’s inimical to the likes of us.’

‘Inimical?’

‘There’s, like, magic force fields and stuff,’ said Beverley.

That would make sense, I thought. It would certainly explain why Nightingale was so relaxed about security.

‘Why are you here, then?’

‘Well,’ said Beverley, ‘when a mummy river and a daddy river love each other very much …’

‘Funny.’

‘Mum says there’s some weird stuff at the UCH you should check out.’

‘What kind of weird stuff?’

‘She said it was on the news.’

‘We don’t have a TV,’ I said.

‘Not even Freeview?’

‘No kind of TV at all,’ I said.

‘Brutal,’ said Beverley. ‘You coming out, or what?’

‘I’ll go see what the Inspector says,’ I said.

I found Nightingale in the library making notes on what I strongly suspected was tomorrow’s Latin homework. I explained about Beverley, and he told me to check it out. By the time I got back to the lobby Beverley had risked coming just inside the door, although she stood as close to the threshold as she could get. Surprisingly Molly was standing beside her, their heads close together as if exchanging confidences. When they heard me coming they separated with suspicious speed – I felt my ears burning. Molly scurried past me and vanished into the depths of the Folly.

‘Are we taking the Jag?’ asked Beverley as I put my coat on.

‘Why, are you coming with me?’ I asked.

‘I have to,’ said Beverley. ‘Mum told me to facilitate.’

‘Facilitate what?’

‘The woman that called it in is an acolyte,’ said Beverley. ‘She won’t talk to you without me there.’

‘Okay,’ I said. ‘Let’s go.’

‘Are we taking the Jag?’

‘Don’t be stupid,’ I said. ‘UCH is walking distance.’

‘Aw,’ said Beverley. ‘I wanted to take the Jag.’

So we took the Jag and got caught in a traffic jam on the Euston Road, and then spent another twenty minutes looking for a parking space. It took us, I estimated, twice as long to drive as it would have to walk.