He saw her customary sardonic look. Every month Alison decided that she needed to get together with him and Josie to smooth everything over, and Julian was equally opposed to the idea. Ninety-five per cent of that was him knowing Josie wouldn’t take to it. And Alison actually turning up at their house might be the relationship equivalent of pushing the nuclear button. The remaining, wretched five per cent was the part of his mind he didn’t let into the driving seat under any circumstances.

“How in trouble are you?” Alison asked.

“Not too much, not me. But…this damned business is the gift that keeps on giving, isn’t it? Sprouting operations like mushrooms. It’s looking like I’ll get Herringbone and Stewey’ll oversee Mouser, at least until they turn out to be the same thing.”

“Which they will,” Alison confirmed.

“Which they will,” echoed Julian, “though I can’t find any way of explaining why I’m certain of it.”

“I don’t suppose you can.”

Both cases involved mysteriously disappearing communications which came and went without leaving any tracks at all. The message to White, the data archive that Alison had been given brief access to, the text message from Mallory to Pryor, and now perhaps some ghost message received by Khan. Someone was playing with extremely advanced telecommunications tech, something that could hide from scrutiny and walk through any security they could devise. That could, maybe, even establish a connection to an offline machine. The stuff of utter paranoia that, if it was true, would see them relying on huge libraries of paper files as though the last five decades hadn’t happened.

Flatland, he thought, remembering Alison’s anecdote about the stockbroker firm. He imagined the 2D security services of Flatland trying to defend their secrets against a 3D infiltrator. One who could look within their sealed safes, access their little flat difference engines…

“You look ill,” Alison told him frankly.

“This case is making me ill.” He gulped down too much too-hot tea and choked out, “What’s Mouser turned up, then?”

“Mice,” she said. “Far too many mice. Spiker. Someone’s either done an exemplary job in record time or this is a stack of unsolved evidence that’s been doing the rounds from op to op for a while. I’ve got material here from Ops Racetrack, Moraybleak, Cartwright, Bluepeel and Hertzelectric.”

“Hertzelectric,” Julian repeated. “Wait, was that…?”

“Willoughs,” she said, naming Julian’s old mentor. “This was the last operation he helmed. All of these are top secret, and several of them involve the Department of Sci and Tech. And while some of them had happy conclusions, all of them had at least one loose thread that nobody could ever tie up. Now it’s Op Mouser’s problem, and maybe yours as well.”

“So what’s the link?” Julian asked.