The snark died on Khan’s lips. “Yes, well,” she said, deflated. “It sounds dreadfully treasonous when you say it like that. I’ll have to assume that if GCHQ was fully able to appreciate the facts they’d probably want me to save the world. Or indeed the universe. If it can be saved.”

Lee still couldn’t get her head round it, but the other woman’s sober manner chilled her. “How?” she asked.

“Saved? Fuck knows. I think they want a meeting of the minds, but I hope to buggery they have more than just mine.”

“No, how will it end?” Fire, zombies, pestilence, war?

“Maths,” Khan spat dourly. “I mean, it’s the universe—it’s not like you can push it under a bus, love. But one thing CITS postulates is that there are certain parameters and dimensions that feed into the nature of the universe—above and beyond the basic forces we take for granted. The whole theory came about as an attempt to explain where most of the universe was. All that matter and energy we can’t lay our hands on. But by the time I got in the game, the focus had shifted to whether this space existed, the space where matter might be hiding, and what you could do with it. Or at least, we were all for investigating the first question, and the people paying us were more after the second.” At Lee’s look, she shook her head and rolled her eyes. “Spy stuff, love. Cracking codes, accessing encrypted data. Theoretically, if you can move your enemy’s data into CITS, you can do what the fuck you like with it. There’s no regular encryption that would confer any protection or have any meaning there. Except we could never get the idea to work in practice, or figure out how to protect our data if anyone else did crack it. Then there was a shift of personnel, and suddenly nobody wanted to keep us in fast cars and martinis any more.” She raised an eyebrow. “When this is done and we’ve saved the universe, I’ll tell them I could do it now, given six months and a decent stipend. I’ve seen how it can work. Fucking simple. If only I’d sat down and thought about it in what is a completely unintuitive and, may I say, frankly inhuman way, I’d be right back at GCHQ asking for my old job back about now. However, my new contacts also showed me something utterly terrifying. A very cogent and succinct proof that the various key parameters of the universe—the ones that CITS proposes—are not only real but are going south. And this is happening in such a way that everything, everything, is going to go out like a candle in the appallingly near future.”