‘Yes,’ said Hepton, ‘I’d like to speak to Nicholas Christopher, please. He works in control.’

‘I’ll see if I can find him. Who’s calling?’

‘It’s his brother, Victor.’

‘Hold on.’ The phone went quiet.

Hepton bit his bottom lip, then changed his mind and bit his top lip instead. Someone was coming down the stairs. A fat man in shirt and tie: one of the diners from upstairs. He pushed open the door to the gents’ and, once inside, started whistling the background music from the restaurant’s hi-fi. Hepton turned his attention back to the amount of money he had left. The LCD was ticking down, but there was still plenty of time.

He hoped Nick Christopher would recognise the code. One night, they had gone off base to a local pub, where the landlord had informed them that there was a disco in the village hall. After a few beers, they had visited the disco, and Christopher had dragged them onto the dance floor to introduce themselves to two young women.

‘I’m Nick,’ he’d shouted over the music, ‘and this is Vic. Nick and Vic.’

In private, that nickname – Vic – had stuck to Hepton for a few weeks, producing a smile every time as it reminded them of that night and that disco.

The receiver suddenly came to life.

‘Brother Victor,’ said Nick Christopher knowingly. ‘I thought you were on holiday?’

‘I am. Can you talk?’

‘Yes.’

‘I mean, is there anyone with you?’

‘Well, I’m at my console.’

‘So there are people around you?’

‘Not many, but yes. Look, give me your number and I’ll call you back.’

‘Okay, but hurry.’ Hepton recited the telephone number and put down the receiver. A good portion of his money, unused, came clanking out, and he scooped it back into his pocket. The phone started to ring. ‘Yes?’ he said.

‘Okay, I can talk now.’ Christopher’s voice was not as hale and hearty as it had been in the control room.

‘What’s happening, Nick?’

‘I don’t know, Vic. It’s been pretty weird here since I last saw you. Fagin asked me if I had any idea where you were. He said he needed to contact you about something. And now … we’re moving out.’

‘What?’ Hepton’s face creased in puzzlement.

‘Moving out. The place is being closed down temporarily. Something to do with fitting a new system. I don’t know, something like that anyway. So everybody’s getting two weeks’ R and R.’

‘But what about Zephyr?’

‘She’ll be stationary. There’s going to be a skeleton staff to keep an eye on things. Fagin and a few others.’

‘What others?’ It was beginning to fall into place now.

‘I don’t know. But none of us. So, anyway, why did you call?’

Hepton had almost forgotten himself. ‘Oh,’ he said, reminded. ‘I’ve got a big favour to ask.’

‘Name it.’