‘It’s a particle accelerator,’ Angelika explained as the man moved the vibrant, insubstantial machine to examine its innards.

Harri noticed circuits, tiny generators, and myriad parts she couldn’t even pretend to recognize.

‘It’s a machine that helps researchers understand the building blocks of the universe. This team are working on making design improvements to the next generation of accelerators,’ Angelika said, before she stepped forward and pressed a button on an intercom panel. ‘Dr Abiola, there’s someone here to see you.’

A tall, slim, regal woman glanced over. Her voice came through the speaker. ‘Just give me a moment, Ang.’

Angelika left the intercom on, and Harri heard the gloved man muttering to himself as he examined the ethereal components. There were two others in the room with him and Dr Abiola – a Chinese man who looked to be in his mid-twenties and who seemed to be inwardly chuckling at a joke, and an intense-looking South Asian woman in her early thirties.

‘I think it’s good to go,’ the gloved man said.

Harri caught Dr Abiola flash a look that suggested she thought otherwise.

‘Reassemble,’ the gloved man said, and the holographic machine came together.

A low hum filled the observation area as the hologram simulated the operation of the particle accelerator. Harri sensed something was wrong immediately. A housing near the top of the machine began vibrating, and the hum turned to an ugly grind.

‘End simulation,’ the gloved man said, and the machine froze instantly. ‘I don’t understand it.’ He craned forward to examine the projection, his frustration evident. ‘I can’t get the tolerances right.’

‘May I?’ Dr Abiola asked, gesturing for the glove.

He handed it over, and Dr Abiola slid it on. She manipulated the hologram, disassembling the machine in a way that Harri found hypnotic. Shimmering sections floated through the air, gliding around Dr Abiola like strange ghosts. The others looked on in awe, and even though she couldn’t understand what was happening, Harri got the impression she was watching a genius at work.

‘You were close, Tarek,’ Dr Abiola said, replacing one of the parts with another she brought up from a menu directory. ‘I’d suggest swapping the generator with a series six device.’

She removed the glove and handed it to Tarek, who somehow managed to look both exasperated and grateful.

‘I should have thought of that,’ he said. ‘The tolerances . . .’

‘It’s OK,’ Dr Abiola assured him. ‘That’s why we have simulators, rather than a billion-pound prototype,’ she gestured at the hologram. ‘If you’ll excuse me.’

She stepped away from the group and glided towards the door, eyeing Harri all the way.

‘Can I help you?’ she asked as she entered the observation area.

‘Dr Abiola, I’m Harriet Kealty. Thanks for agreeing to see me. I’d like to ask you some questions about David and Elizabeth Asha, and Ben Elmys.’

Her smile fell and her face clouded over. ‘I see. Thank you, Angelika,’ she said, and the young PhD student nodded and withdrew. Dr Abiola waited until she was gone. ‘Why don’t we go for a walk?’