“You know what I was working on, Alice?” Khan leant on the sofa back and crossed her legs primly, shades of moll to Alison’s gangster. “Cryptic Informational Transformation Space. Codebreaking, actually. We wondered if you could take computations out of regular space and put this data into a purely theoretical, extradimensional space. If you could see and work with that data in this space, you could basically waltz past any security. There would be no barrier between you and the information you wanted to get your grubby little mitts on. Government very interested, obviously, threw lots of money at it, paid off my mortgage and then some, believe me, love. Only it didn’t fucking work and then they cut funding. Which was frustrating because I know I could have got it to work. However, my peers said it couldn’t be done, and the review board listened to them. Except it can be done, because that’s how these jokers called me—straight to my phone without a network or anything, using CIT-Space. No passwords, no barriers. It turns out the space isn’t so theoretical. Those extra dimensions exist, at ninety degrees to everything else. And I can see I’m losing you.”

“Dimensions,” Alison prompted gamely.

“Height, breadth, depth—forget time for a second, because that’s the screwy one. But there’s another direction of travel involved here, or from here to there. There are other worlds, but they are still versions of this one. Branches, this lot call them. Very big on nature imagery, real murder-hippies.”

“Parallel worlds?”

“Other Earths,” Khan confirmed. “Always have been, maybe, separate, inviolate. Except that’s the problem. There are fissures, they say—there are spaces between the worlds that can be used for CITS-style fuckery. And there are also…collisions. Intrusions, basically. The different worlds are now leaking into one another through these fissures, and it’s getting worse. This lot have a way better understanding of all this—it’s basically National Curriculum over there, they do GCSEs in it probably. So they’re trying to work out if there’s a cause—and whether it can be stopped. And for that they recruited me. I was probably easier to get hold of here than Xian or Ravichandra, who are the only other people in the field who might get their heads around it. Or maybe they have them as well.”

“Or maybe they want to control whatever it is. Capturing the only people who could stop them could be a good prelude to interdimensional invasion,” Alison pointed out.

“My, you are a suspicious one,” Khan said.

One of the men abruptly slapped his hands together, standing and shaking his shoulders. His breath plumed, and Alison saw a rime of frost on the seams of his torn shirt.

“That—what is that?” she hissed urgently. “The cold, the…What are they doing?”