“Exactly. Here, this is the next camera along.” She tapped a command and the image changed, showing a slightly different angle of the same stretch of hallway.
“You still can’t see the door.”
“The corridor curves. Add that to the support strut there, and the view of the door is blocked.”
“Well, what about one of the other cameras?”
“I’ve checked. None of them can see the door to that unit.”
“How is that… no, it doesn’t matter. To open that door the killer had to walk along the corridor, there has to be a picture of them.”
“No, Ely, that’s what I’m telling you.” Her fingers moved. The screen split. “These are all the cameras along the corridor, in both directions. This is just after shift-change. You see, there? There are the Greenes. Now watch.”
The corridor filled with people and, one at a time, they drifted into their unit for their shift’s sleep.
“This will save some time if I just speed it up.” She began tapping out another command.
“It would save even more if you just told me,” Ely said.
“Sorry. Okay, basically no one went along that corridor until the next shift-change. No. Sorry, no, what I meant to say is that no one is recorded going along that corridor.”
“You mean this is a ghost?” Ely asked without trying to hide the scorn in his voice.
“You mean do I think this is the descendent of someone who got stuck outside after the Towers were sealed and somehow managed to survive down in the tunnels? No, of course not, that’s just a story. Besides, the tunnels are flooded. No, I meant that I’ve been looking at it over and over again, and I think you can get down that corridor, all the way to the door to that unit, without being recorded by any of the cameras.”
“But we’d still have a record of their position in the Tower.”
“Not if they went off-net. That’s what I’m trying to tell you. We don’t monitor the people, we’re monitoring the wristboards. That’s how we know where everyone is, what their heart rate is, when they ate, when they’re at work. When they sleep, the pods take over. But if they take the wristboard off, the system doesn’t know where they are.”
“So, to become invisible, all you would have to do is take off your wristboard?” Ely asked.
“Well, yes and no. I mean, the cameras would still record that part of the corridor. So you’d have to know where they were and, for instance, that these two, here, rotate, and you’d want to know the timing, but you could watch it and learn.”
“And you knew about these blind spots?” Ely asked, failing to hide the accusation in his voice.
“I knew there were some, sure,” she said. “But I didn’t know there were so many. I mean, no one could, not unless you went through the schematics and crossed off every inch of corridor against an image.”
“Or if you stood in a corridor,” Ely said, “and looked up, saw the camera move, and realised that you were no longer being recorded. It would take years of planning.”
“Even then you’d have to have access to the system,” she said.
“Which we know the killer did, don’t we?” he asked. “No alarms went off.”
“That’s a different part of the system.”
“If our killer had access to one part, then why couldn’t they have access to all of it?” Ely asked.
“Because they moved the camera. So we know they don’t have access to everything, we just don’t know how much.”
“Right.” Ely felt a flush of embarrassment that he hadn’t realised that himself. “So let me get this straight. They can access the alarms and turn those off, they can open the doors, but they can’t erase the camera footage?”
“That’s what it looks like,” Vauxhall said.
“And there are, what, two hundred and fifty families in that shift eligible to use that room?” Ely asked.
“Two hundred and sixty-seven.”
“So, statistically speaking, having moved the camera, the killer wouldn’t have to wait more than ninety days for any one family to use that room.”
“Yes, they’re allocated randomly to ensure no one develops any attachment to them.”
“Interesting. And it’s been fourteen days. Maybe this had nothing to do with the Greenes then. Maybe…” he didn’t finish the thought. It was to terrifying to say out loud.
“What?” Vauxhall asked
“Well, what if the Greenes weren’t specifically targeted. What if it was just about disrupting production?”
“You mean sabotage? Why?” she asked.
“I don’t know,” Ely said.
“Well, where do we go from here?”
“There’s something I read once.” It was one of the few things he could remember from the forensics textbooks. “Absence of evidence is evidence itself. So the killer can turn off the alarms, they can hide from the cameras, they can make it seem as if they weren’t in that corridor but,” and Ely smiled as he realised he was right, “they can’t hide their presence from the system.”
“You mean the wristboard data? I told you that no one was recorded using that corridor during the time of the murder.”
“Yes. And that means someone took it off,” he said. “They had to have left it somewhere. But that means that for the time the murder took place, the killer went off-net. We believe the murder happened at three a.m., that’s the middle of a shift. Can you think of any reason at all for anyone in the Tower to take their wristboard off at that time? Well, can you?”
“No, none at all.”
“So,” he said, “instead of looking to see where they were, just look for who wasn’t anywhere. Do you see?”
“Okay,” Vauxhall said, as she returned her attention to the screens. “That makes sense. Hang on.”
“How long will this take?” Ely asked.
“I said hang on… here.” A list came up on the screen.
“Who are they?” he asked.
“That’s all the people who were off-net during the time of the murder.”
“All of them? But there are so many.”
“There are forty-seven people,” she said.
“No,” Ely said. “Forty-seven suspects.”
He picked up his helmet.
“Where are you going?” Vauxhall asked.
“To interrogate them,” he said simply, as he walked out of the door.
He’d made it twenty paces before an alert came up on his display. He had an incoming call from Chancellor Stirling. Bracing himself, he answered it.
“Murders, Constable. Murders! Why didn’t you inform me directly?” the Chancellor demanded.
“Ma’am, I was waiting until I had something to report.”
“You don’t think this ruinous loss of production was something worth reporting? Do you know how much labour has been lost?”
“About a quarter of a million hours ma’am.”
“Our current estimates,” a man answered, “put it at three hundred thousand. It is likely to be far higher.”
Ely knew that voice as well. It belonged to Councillor Henley, the man Stirling wanted to take control of Tower-One. He was expected to win. His opponent, Chester from Tower-Five, had made some ill-advised comments about population increase ten years ago. There was no doubt as to who had leaked the recordings of them to the newsfeeds. There were no candidates from Tower-One standing. The Assemblies had a long tradition of not wasting workers on something so frivolous as politics.
“Three hundred thousand hours lost, all from Tower-One,” Henley said. “What do you have to say about that?”
That it was a matter for Councillor Cornwall, Ely thought. “As I said,” he replied. “I wanted to make some progress with the investigation before reporting in.”
“Well get on with it,” Stirling snapped. “Why were the Greenes killed?”
“I don’t know ma’am, but,” Ely added quickly, “I believe it was sabotage.”