“The evidence is how Sam acted. Kevin, you knew her. You mentored her. You practically raised her. She was loyal.”

More loyal than I am, Holtzmann thought.

Nakamura said nothing for a while. The car switched lanes of its own accord to fall in behind a long row of vehicles, then pulled up close to the one ahead, just inches from bumper to bumper, drafting, saving fuel.

“Shu’s dead now,” Nakamura said. “How would that affect Sam?”

Holtzmann brought his hands up to his face, closed his eyes for a moment, then pulled his hands away. “I don’t know, Kevin.”

“You don’t know?”

“It depends. How did Shu program her? Did she turn Cataranes into a puppet steered by remote control?”

In his mind the Secret Service man’s gun came out out out, and fired, and fired.

“…Or did she put in something more complex? Something deeper?”

Human missiles leveled the shooter, and Holtzmann turned, looking for the President. Joe Duran screaming in his ear, “How did you know, Martin? How did you know?”

“It doesn’t make any sense,” Nakamura said.

Then the world exploded in Holtzmann’s memories, hurling him through the air.

“What?” Holtzmann said.

“If Shu turned Sam, she could have sent her back to ERD as a mole. Or whisked her and Kade off to China. Shu had to know the loft was an ambush, that it was a mission to get close to Prat-Nung.”

“I don’t understand,” Holtzmann said.

“Why did Shu let Sam and Kade walk into that situation, Martin? If she’d already turned Sam, then she knew the loft was an ambush. Shu was recruiting Kade, but she nearly got him killed.”

“Shu was trying to protect Ted Prat-Nung,” Holtzmann replied.

Nakamura shook his head. “No. Shu and Prat-Nung knew each other. She could have just warned him away.”

Holtzmann dropped his face back into his hands. He was so tired. So very tired. He could feel the aches starting again, the clammy sweating, the chills deep inside.

“I don’t know, Kevin.”

“Who had the most to gain?” Nakamura asked, almost to himself. “The way to find the cause of an event is to understand who had the most to gain from it.”

The car activated its turn signal, then switched lanes on its own, into the exit lane that would take them to Holtzmann’s home.

“Lane,” Holtzmann said. “Kaden Lane had the most to gain. He escaped because of Sam.”

Nakamura nodded. “Yes. That was my conclusion as well.”

And the movie started again in Holtzmann’s mind. The hot July day. The white plastic chairs. The President blathering on. The encrypted Nexus traffic. The Secret Service agent in black suit and mirrored glasses, reaching into his jacket…

“Could he do it?” Nakamura asked.

…The gun coming out in slow motion...

“Yes,” Holtzmann replied, sick to his stomach. “I think he could.”

… Coming out, out, out…

“One last question, Martin.”