The images streamed from the CIA satellite covering this section of Estonia were so clear you could have seen a pebble in the grass. They were looking at a collection of outbuildings, but the screen next to them had a wider view of a village. ‘Puhlova,’ Kate said.

‘You know it?’ Julie asked.

Kate had met a Russian Army colonel there about a decade previously. He’d promised information on the state of Russia’s nuclear arsenal in return for very large cash payments, but she’d not believed a word he’d said and had turned down his offer flat.

‘It changed hands two months ago,’ Julie said. ‘The new owner is a business registered in Helsinki.’

Danny closed in on the tyre tracks in the mud. Kate could see exactly what he was thinking: a lot of tracks, too narrow for a tractor, much too wide for a car. ‘Hard to be sure until we see some movement,’ he said. He zoomed in on a patch of grass just outside one of the buildings. Cigarette butts lay everywhere. ‘A lot of workers for a small farm.’

‘You find anything on the firm?’

Julie shook her head. ‘A holding company in Geneva, another in Bern, then to Belize and finally Panama. If it’s not the Russians, it’s someone else with a lot of cash to spend covering their tracks.’

‘How far back can you go?’

Kate’s question was to Danny and he pulled up another screen and started to rewind the footage on it rapidly. ‘Only a week, but that’s what’s weird. I checked the Met Office records. It rained really heavily nine days ago, so these tracks would have been obliterated if they’d been there before then. They must have been made after the deluge. But there’s been no movement in or out of these barns in the past week.’ He stopped rewinding and minimized the screen, pulling up another. ‘We started casting around. We looked closer to the border . . . but neither of us could find anything. So then we went further away.’ He froze the footage and closed in on a building by the Baltic. ‘This is a hotel in Silamae on the beach. A congenial place to plan a coup.’

Beneath a lean-to beside the hotel, the rear wheels of several motorbikes were clearly visible. ‘Not an army, exactly,’ Danny concluded, ‘but maybe the vanguard.’

‘That’s great,’ Kate said. ‘What’s that on?’

‘PCR2.’

‘See what else you can find on both sides of the border.’

Kate left them to their work, then thought better of it and doubled back. She sat again, so that she was close to Danny: the people at the other end of the ops room would be out of earshot. ‘Talk me through faking a video.’

‘What kind?’

‘If someone wanted to create a fake kompromat video, is it possible to do it convincingly enough to fool us?’

‘I guess that really depends. What kind of video are we talking about exactly?’

‘A sex tape.’