Clark tapped the frames of his glasses and the walls of light flickered out, leaving behind the rather mundane-looking auditorium. She felt like going around tapping and knocking on things to make sure they were solid.

“This way,” said Harman. “We don’t normally allow people down below. That’s where we keep the real magic.” He raised his eyebrows at Britta and actually looked quite excited. It made her think she was about to enter Willy Wonka’s chocolate factory. She doubted there’d be any Oompa Loompas or chocolate waterfalls down there, unfortunately. But she still wanted to see Nigel in the flesh, as it were.

“This way, then,” said Clark, a lot less excited. He was a lot less emotional altogether.

They were led back to the main foyer, to the lifts. They got inside one, no different to the rest, and Harman placed his hand over a panel. It was like in a movie where the high-tech security required a palm print to allow access. Since this pale had been built by obvious nerds, she assumed the reason it mirrored the world of sci-fi movies wasn’t a coincidence.

Geniuses in the past had been odd and unique, and had often been marginalised for it. Modern-day geniuses presented themselves as a collection of well-established eccentricities, like a hip hop album of classic show tune samples.

It made Britta very suspicious of their motives. Did they want to create something that worked well, or something that looked cool? They could do both, but people rarely did.

The lift started moving downwards.

“Is it a long way down?” asked Dad. He seemed quite excited by the prospect of being allowed into a restricted area, although Britta suspected he was hoping for some kind of secret Bond villain underground facility, possibly with a nuclear submarine parked in a diving pool.

“No, not very,” said Dr Reedy, just as the lift stopped and the doors opened.

There was a hallway with strip lighting overhead and rooms on either side with glass walls. As they walked down the hall, Britta’s head moved from side to side, checking out the rooms. The layout could have been any office building. Small, functional rooms with someone sitting at a desk, working at a computer. There were no windows, but each room had a large screen on the back wall, some showing a pretty view, others goldfish.

There was a vending machine that sold chocolates and coffee at the far end. It wasn’t very Bond-like. She hadn’t seen a single guard, armed or otherwise.

Some heads did look up as they strolled past, but no one came rushing out to greet them. She was with the bosses, so they were unlikely to be stopped and asked for their IDs.

They took a left, a right, down a small flight of steps, and finally came to a door that looked a bit more solid. It had another panel requiring a palm-print, and also a keypad with a hood over it, making it harder to identify the numbers pressed.

Harman held the door open for the others to come through into what looked like a cloakroom.

There were hooks with big, heavy parkas hanging from them. They were green with orange lining and fur trim. Nothing very remarkable.

“Grab whatever you think will fit, it’s just to keep the chill out. Not sure we have one in your size,” said Harman as he put on one of the coats. “Try this.” He handed Britta a coat that looked no different to the others. Massive.

It was fairly cool down here, but nothing uncomfortable. The next room was apparently going to be in Siberia. Britta put on the coat, which reached down below her knees. It was very comfortable, if a little swamping. Dad had to help her fold back the sleeves so she could use her hands.

The door at the other end of the room didn’t have any security requirements. Everyone was zipped up and ready to go. Harman opened it, pulling it in with a little effort and holding it. Clark went through first, after removing his glasses.

The drop in temperature was very noticeable. Her legs prickled like cats were climbing up her trousers with their claws occasionally digging into her skin. Her breath appeared in little white clouds.

They were in a glass cube, outside of which there appeared to be some kind of warehouse. The lighting was limited to their immediate location, but rows and rows of shelves disappeared into the distance. It was the sort of thing she imagined Amazon had in every city of the world, only filled with household goods and cheap electronic gadgets.

These shelves were filled with big metal boxes with small LED lights flashing occasionally. It wasn’t like the array of coloured Christmas lights you might expect of a supercomputer, it was more like the ones on your washing machine, telling you which cycle was running. Small and discreet.

Inside the cube with them were two people, a man and a woman, both in parkas, although theirs were unzipped and hanging loose. They wore fingerless gloves and each sat at a computer terminal.

“Hey,” said the man enthusiastically. “Visitors!”

The woman seemed less excited and just nodded.

“Don’t mind us,” said Harman. “We’re just going to say hello to N-27.”

“I could give your friends the guided tour,” said the man, clearly bored out of his mind.

“That won’t be necessary,” said Clark. “I hope you’ve got those readings for me.”

“Of course,” said the man, in the way kids at school said when asked if they’d done their homework when they hadn’t even started.

Harman opened another door and now the temperature really fell. Britta’s face got tight. Her hood rose over her head as Dad lifted it up from behind.

The lighting moved with them as they walked. The floor was cement, the roof was made up of banks of fluorescent lighting activated by motion sensors. Britta looked back. The glass cube was a little island in the dark.

They reached an open area with a desk and a chair. The desk was actually a console, with buttons built into it. A lot of buttons, like the inside of an aeroplane.

“This is Nigel,” said Harman. He flipped a switch on the console and a single green light came on. “Say hello, Nigel.” There was no response. “Okay, then.” He switched it off again. “Shall we go back?”

“Is this where he speaks to you?” asked Britta, getting closer to the console.

“He used to,” said Dr Reedy. “He hasn’t been in touch for a while, I’m afraid.”

Britta ran her fingers across some of the buttons and switches. There were no labels. She could sense the two men in charge tensing as she touched their personal toy, just like Dad and his boxed action figures.

She flicked the switch that Harman had used. “Hello? Nigel?”

There was no response. The vapour from her words disappeared and her nose felt cold.

Then the other lights on the console lit up, spreading to the metal boxes around them until they were surrounded by a ring of tiny flashing lights.

“Hello, Britta.”