Alison wooed her by tracking down her Iain M. Banks fanfic and complimenting her on it, which got her closer than any of the previous interviewers. In particular she discovered that Charen was still in and out of the SFI offices, despite having been theoretically laid off following the dramatic death spiral of the firm.

“It’s not our fault,” she said angrily. She was escorting Alison through the deserted trading floor, then into the hidden corridors and rooms beyond. Here, as she put it, the real work went on.

“Nobody’s saying it’s your fault,” Alison lied.

“Our,” Charen repeated. She had a hint of a Slavic accent still, which made her stop-start speech harder to understand when she got going. “And now they’re going to come and try to turn it off again—because of something like money. We will have to do something.”

Alison felt oddly certain that “we” didn’t mean Charen and her boss, but the system itself. By now they were amongst the servers, in rooms cold enough that her breath plumed white. Charen rounded on her with a gleam in her eye. “Can you hear it thinking?” she asked.

Alison could only hear a multitude of fans and the air conditioning going full blast. “Does it have to be this cold?”

Charen laughed at her. “This isn’t cold. This is just the system waiting. When it gets working, then it’s really cold. That’s when I put my jumper on; that’s when I put my coat on. There’s ice.” Her smile should have seemed deranged, but Alison recalled it as weirdly innocent.

She found the logs for the server room temperature. Nobody else had thought to look at them, because why would they? Either something was broken or the room fluctuated from fifteen degrees above to seventeen below. Alison did a little research on the cooling systems involved and worked out that this was impossible. The heat from the machines should have kept the place uncomfortably stuffy at the best of times. Except she’d stood there, in that chill. Not frostbite temperatures, but still colder than it had any right to be.

A small step, from there, to start correlating the temperature shifts with the trading. Things went wrong when the server room became warm, every time. One of her predecessors had even pinpointed to the minute when the computer’s decision-making seemed to go off a cliff, and Alison could match it exactly to her temperature graph.

Charen looked mulish when confronted with this, during a formal interview. She pretended not to know anything about it, which Alison saw through. She wouldn’t volunteer anything else either. Pressed further, she just stood up to go, the interview unilaterally over.

“They’ll think you sabotaged it.” Alison’s last gambit, but it froze Charen in her tracks.