My phone battery was low. I brought up real-time satellite imagery of the Kazakh border with Russia. This was what Joanna had been doing in the internet café, I realised now: watching the creep of war. The hacked data showed her something that had got out of control.

Imagery was vague; Russian troops were more than capable of going invisible if they chose. There were no more updates from Aliya in Astana, or her other personas. No reply when I messaged her, which was understandable. I logged into her phone, switched the mic on, heard a crowd chanting. She had joined the protest. She could have chosen safety and she chose history.

I tried Walker, then the Vectis office. Both lines were dead. I stood at the window and stared out at the corrugated walls of the industrial estate. According to local news, Zhaparov was due to address the Independence Square crowd in an hour, flanked by senior officials from Russia. He was branding it a mass vigil, an attempt to keep the square occupied by grief rather than anger: Kazakhstan united against terrorism.

In 2014, ISIS published instructions for building and deploying vehicle-borne explosives. They encouraged targeting mass gatherings. They advised on components that weren’t going to trigger security tripwires, and suggested waiting to construct the device until just before the operation for maximum discretion.

Police had seized a laptop containing research on fuel-air bombs along with a detailed satellite image of Astana and surveillance photographs of public squares.

Fuel-air meant thermobaric. Thermobaric explosions were unlike anything else. Mix in enough petrol with your military-grade explosives and you got a second blast wave as the air itself caught light, sucking up all the oxygen. Most forms of defence were useless; the fuel cloud flowed around objects and into structures. What tended to kill people wasn’t just the pressure wave but the subsequent vacuum, which tore lungs apart.

In a crowd like Independence Square, there would be more than five or six hundred in the kill zone.

But how would you get the vehicle through? No parked cars, area checked by sniffer dogs, airspace closed. Blocks on every approach road. I sat on a swivel chair in the abandoned office, hearing the peace outside. I made a fist of my left hand then opened it and stared at the scar.

Reza called.

‘We have the last location of Joanna’s cellphone.’

FIFTY-TWO

The location was two miles out of the city. I coaxed the car to seventy miles per hour, prayed that its wheels would hold on the icy road.

The coordinates led me into nothingness: salt flats as far as the eye could see. I considered the possibility that Reza’s readings were out, or even that GPS signals were being scrambled, which wasn’t unheard of during states of emergency. A mile later, as I was about to turn back, I saw something.