Izzard nodded, deep in thought but enjoying himself.

‘This base, the one they’re using, it’s south of Buchan?’

‘Yes, someplace where it gets dark earlier than it does in Scotland at this time of year; somewhere down here.’

‘There are plenty to choose from.’

‘Not very many would fit the bill. It should be easy to find which one it is.’

‘This begs two rather large questions: why, and how?’

They had reached the café. There were no taxis outside now. Shifts had either ended or not yet begun. The glare of strip lighting made Hepton squint as they pushed through the door. A small, sweating man was standing behind the counter, wiping it down with a rag. He looked up as they entered.

‘This is a late one for you, Graeme,’ he said to Izzard.

‘I wouldn’t mind, Alfie, but the overtime rate is diabolical. Give us two of your special breakfasts, will you?’

‘Coming up. Where’s my flask?’

Izzard opened his arms in apology. ‘Sorry, Alfie. I forgot. It’s back at the lab.’

‘Well, never mind. Do you want any tea?’

‘Coffee for me, black and sweet. What about you, Martin?’

‘Black, no sugar, please,’ said Hepton.

The man nodded and started to work.

‘How and why,’ said Hepton. ‘Yes, you’re right. But we’re very close to answering both. I can feel it. I can almost answer the “how” right now, though it’s only guesswork.’

‘Go ahead.’ They had seated themselves on padded benches either side of a Formica-topped table. Hepton rested his elbows on the table, hands supporting his head as he thought things through.

‘Well,’ he said. ‘A shuttle, the Argos—’

‘The one that crashed?’

‘Yes, the one that crashed. It was up there launching a communications satellite. Except the satellite wasn’t just your normal COMINT satellite, it was an intercept.’

‘An intercept?’

‘Yes. Its purpose was to lock on to Zephyr. While it was locking on, Zephyr’s transmissions went haywire. But nobody minded that, because as long as the transmissions returned eventually, everyone would put it down to a glitch, nothing more. Some top brass from the military were on site when it all happened, just to check that the operation went smoothly. It did, more or less. Except I noticed how pleased they were looking, and one other person, a friend of mine, caught a hint of the interference. They murdered him and wiped his disk.’

Izzard whistled softly. Hepton paused, then continued.

‘So what do we have? We have Zephyr apparently back to normal, except that it isn’t, not quite. Because whenever we lock on to one particular spot – Buchan – the other satellite breaks in and transmits its own pictures to Zephyr before they’re transmitted to the ground station.’

Izzard was shaking his head. ‘This is too big for me,’ he said. ‘I’m used to bank robbers and spies, not conspiracies in space.’