Page 116 of The Towering Sky
“You had been tracking Mariel’s movements since Dubai, hadn’t you?” he asked, utterly aghast. But he needed to understand. “Just waiting for the right moment, for her to put herself in a vulnerable position. And then she walked home alone, in the dark, and you realized it was the perfect chance to kill her and make it look like an accident. So you hacked one of those big transport bots and made it knock her into the water,” he guessed.
“Yes,” Nadia told him.
“You were afraid she might send me to prison, and so youkilledher?”
“I killed her because if she stayed alive, there was more than a ninety-five percent chance that you would end up incarcerated, and more than a thirty percent chance that she would try to kill you! I did the calculations over and over, Watt. Every outcome ended up with you in prison, or worse. Except this one. The only reason Mariel didn’t hurt you is because I hurt her first.”
“And that’s supposed to make me feel better?”
“It’s supposed to make you feel grateful, yes. You’re still alive, and free. Honestly,” Nadia added, “I’m surprised you’re feeling so much guilt, Watt. She left Leda to die, and she was going to hurt you—”
“That doesn’t make you god, to deliver some kind ofjudgmenton her!”
The snow was swirling in soft flakes to hit the river. Each time one of the flakes collided with the surface, it melted almost instantly, dissolving into the water like a tiny frozen teardrop.
Nadia didn’t even seem sorry. But of course she couldn’t be sorry, Watt corrected himself, she couldn’t feelanything, because she was a machine; and no matter how many clever jokes she made or ideas she seemed to generate, no matter how many times she knew exactly what to say when he was upset, she was still a machine, and there was no way for him to have programmed her with that elusive human trait called empathy.
Something else occurred to him. “Why did you try and make me think that Leda killed Mariel, when you knew the whole time that she hadn’t done it?”
“Leda was always my backup plan. It wasn’t a coincidence that she blacked out that night—I faked messages from her account to her dealer, asking for higher dosages than normal.I wanted to make sure I had someone to take the blame, just in case.”
“Just in case?”
“I tried to wipe away all traces of what I had done, but apparently my hacking left a trace on that transport bot. Three months ago, in a routine maintenance check, someone noticed that the bot had been tampered with. That was why the police moved Mariel’s case from accidental death to murder—because they realized that someone had used a bot to knock Mariel into the water.”
He blinked, feeling betrayed. “You knew that was the reason the case was reclassified, and you never told me?”
“Of course I knew,” Nadia said, her voice clipped. “I didn’t tell you because you never asked me directly. Until now.”
“What does that have to do with Leda?”
“I worried that you would eventually be drawn into the murder investigation. The police might have blamed you for Mariel’s death, or worse, discovered the truth about me. I couldn’t have that.
“So I let you think that Leda might have killed Mariel. I knew that you would ask her point-blank if she had done it. And after you hacked the police station, I led you to believe that the police were getting closer—that the net was drawing tighter around all of you. I wanted Leda to question her own guilt.”
“Why?”
“I knew that if Leda thought you were in danger, she would take the fall to keep you safe. And I was right, wasn’t I?” Nadia added, sounding almost proud. “That’s exactly what Leda was planning to do. The only thing I didn’t foresee was that Avery Fuller would step in and take the blame instead.”
And it didn’t matter to Nadia, Watt realized, fighting back awave of nauseous grief. One scapegoat was as good as another. Humans were interchangeable to her—except for Watt, the one human she had been programmed to care about.
And it wasn’t as if Nadia herself was about to step forward and confess to the crime.
Watt shook his head. “I still don’t understand. You aren’t supposed to harm humans; that’s your fundamental programming.” He coded that as Nadia’s core directive: the single command that she could never contradict, no matter what subsequent commands were given to her. It was the way all quants were coded, so no matter what happened—no matter if a terrorist or murderer somehow got access to them—they would never, ever harm a human being.
“No,” Nadia said simply. “That is my second line of programming. My core directive is to do what’s best for you. I ran a lot of scenarios, Watt. And I judged it impossible for you to remain safe as long as that girl was alive.”
“Oh god, ohgod,” Watt said slowly. A tingling wind had sprung up, to lash angrily at his face. He felt something stiff and cold on his lashes and realized that he was crying and that the wind had frozen his tears.
It was his fault. No matter what Mariel had done, or might have done, she had still died because of him. Because of an error he’d made when programming a computer at age thirteen.
Watt didn’t have a choice. He turned the boat around and started back toward the dock.
Nadia didn’t ask where they were headed. Maybe she already knew.
LEDA
LEDA STOOD THEREwith the rest of them: the heaving, surging cluster of people on the Fullers’ private landing, all trying desperately to find out what was going on.
