“She didn’t have her phone,” Rigo confirmed. “No visitors except us, and we sure as hell didn’t say anything. There was no way…” Under Julian’s watchful gaze he shifted awkwardly. “She was on the laptop we gave her a lot. Offline, but she was on it. I wondered, afterwards, if someone got round us, somehow. If they were able to get a message to her.”

“It’s being looked at, of course.”

“Of course,” Rigo confirmed. “It was on, open, when I went into the room to look for her. The screen…But this is in my report, okay?”

Julian had zeroed in on that paragraph on first reading, vague echoes of Alison’s experiences rattling about his head. “Tell me, in full.” Because Rigo’s reference to it had been cursory, embarrassed.

“I thought there was something on the screen. When I went in I looked at it, just quickly—I was after h-her, after all, wasn’t I? But there was maths on it. I know I’m no expert, but it was like nothing I’ve ever seen. Later, when we went back, after we knew she’d done a flit, the symbols were gone, as if they had never existed.”

“Wiped? Restored to defaults or whatever?” This was a secure laptop, the same kind that Julian used to work from home. It was supposedly bulletproof, as far as someone messing with it was concerned.

Rigo spread his hands. “They’re looking still. According to them, it was as if the machine had just started up and then not been touched, just sat open for about ninety minutes. Whatever Khan was doing on it, any message someone snuck in…it’s gone. And then there were the notes.”

Julian nodded. “We’ll have to leave that to the experts too. More than our pay grade…”

Rigo nodded grimly. Beside the laptop there had been a handful of sheets of paper covered in notations. He should probably be thankful that Khan had felt the need to work through something by hand or they’d have absolutely nothing to go on. Except nobody could understand it. Julian had already seen terse reports from two other Defence Science and Technology lab physicists who had confessed it was simply not their field. Nobody else in the DST would even venture an opinion; the whole point of keeping Khan safe was that she was one of the few scientists in the world whose field it was. The others were deep within the machinery of other nation states, so sending Khan’s notes to them would probably be grounds for a treason trial.