‘No problem. Nobody calls me Einstein any more, by the way. It’s Nige. Hi, Belle.’ He gave her a timid peck on the cheek. ‘Although, I’m a bit pushed for time, as I told you on the phone. You want to sit, or shall we walk . . . ?’

‘Let’s walk.’

The place was so beautiful. Belle couldn’t stop staring at the fabulous soaring towers of honey-coloured stone, the immaculate lawns sweeping down to the River Cam. The sun sparkled on the water and people steered punts with long poles.

‘So how’s chemistry?’ asked Belle.

‘Demanding,’ he said. ‘I’m working on biophysical and spectroscopic studies of macromolecule structure, dynamics and function.’

‘Of course you are,’ said Belle, laughing. He’d always been the brainiest of all her friends, stunningly intelligent. ‘It don’t seem like five minutes since you were scaring us all to death in the science lab at school, setting fire to things with a Bunsen burner.’

Einstein laughed too. ‘I still do that.’

‘I bet you do,’ she said.

‘You see any of the old crowd much? Davey or Phil? What about Milly? Didn’t your dads work together?’

Belle’s smile faded. ‘I don’t see Davey or Phil. But Milly? Yeah, we live side by side, we’re big pals.’

‘I liked her,’ said Einstein. ‘Nice quiet girl.’

‘Yeah. She hasn’t changed.’

‘So what’s the emergency?’ he asked as they paused by the riverside. Two swans glided past, snow-white and elegant against the dark waters. ‘On the phone you seemed anxious.’

Belle looked at him. ‘I want to describe something to you. And for you to tell me what you make of it.’

‘OK. Go ahead.’

Belle gave him the details of what she had seen at the ‘accounts’ office. She told him about the boiling liquids, the protective suiting the people wore. Everything she could think of, she told him.

Finally, she stopped. ‘That’s it,’ she said. ‘I wondered – do you think they were making glue? Glue for the furniture?’

‘A bit improbable, don’t you think? Why do that in an office? Why not in the main production unit? Was there a smell?’ he asked, frowning.

‘Yeah. It nearly choked me.’

‘Describe it.’

Belle thought it over. ‘Like burning rubber,’ she said.

He looked at her, his face very serious all of a sudden. ‘You’re sure about that?’

‘Absolutely.’

‘Positive?’

‘Yes. Why? What is it? Do you know?’

‘That isn’t glue.’

‘Then what the hell is it?’

‘Belle – this could be serious.’

‘What do you mean?’

‘Look. You dissolve cocaine in ammonia, add water and bicarbonate of soda, then heat it until the liquid boils off. You’ll get a harsh chemical smell, quite toxic. Exactly like burning rubber.’

‘Whoa. Stop. You said cocaine,’ said Belle.