Walker drove east on the interstate, and eventually they would head north, to Palo Alto. It had been twenty minutes since they’d left the fire track. Twenty minutes of Monica’s silence.
“We need to change cars,” Walker said.
Monica said nothing, merely stared out her window.
“We’ll take Granger’s Crown Vic. Actually, we’ll get him to drive us. They’re looking for me and you. Not him. Not three people.”
Monica remained silent.
“We’ll get to your brother’s apartment and see what—”
“What’s the point?” Monica didn’t look at him as she spoke. Her voice was flat, tired, losing hope. “Paul was our lead. What can we do?”
“I got some intel from Paul. A code. We’ll find your brother.”
“Really?” Now Monica was looking at him. “What kind of code?”
“Numbers.”
Monica was quiet long enough for Walker to look across at her.
“What kind of numbers?” she said finally.
“In series of three. Single and double and triple digits, then singles and doubles, singles and doubles.”
“Do you have them written down?”
“Yeah,” Walker said. He fished into his jeans pocket as he entered the outskirts of Beaumont. He handed over the folded piece of paper.
Monica held it, and her hands began to shake, but not from the drugs or the adrenaline.
“What is it?” Walker said. “Are you okay?”
“Did Paul see this?”
“Yeah. Of course. He found it. He thought it was trash code at the end of the first couple of attacks. But I transcribed it. I think it’s something. There’s a pattern in there, somewhere.”
“He said it was trash code?”
“That’s what he said. But there’s a pattern in there, I’m sure of it.”
“It’s not a pattern,” Monica said. “It’s a book cipher. The numbers refer to pages and lines and words in a book.”
“You’re sure?”
“Yes.”
“Which book?”
“I have no idea.”
“But you’re sure it’s a book code?”
Monica looked out the window, the paper loose in her hands. “Yes.”
“Maybe Jasper left the book at his apartment?”
“Maybe.” Monica looked ahead.
“There were hundreds of books in his apartment.”
“Yep.”
“But he’d probably need to have a copy on him, of this particular book.”
“No. He’d have memorized it.”
“Memorized the location of every word in each line on each page of a book? That’s impossible.”
“Not for Jasper. Not if he knew the placement of the letters, memorized them. He deals in numbers all the time—he’s a freak with them.”
Walker found the second motel on the highway, where the decade-old silver Crown Vic was parked. Granger had followed his instructions.
“You look worried,” Monica said.
Walker glanced at her as he slowed the truck but continued past the entrance.
“What you said about Jasper,” he said. “If he knew the letters and memorized them . . .”
“What about it? What are you thinking?”
“I’m not sure yet.”
“Well, I am sure.” Monica nodded. “He used to do book ciphers as a kid. Obsessive. My father taught him. So, he has a favorite book, or two, or ten, and he’s memorized letter positions in them. Simple as that.”
“You use that word a lot with your brother—obsessive.”
Monica didn’t answer.
“So, he used a book cipher to get a message out. To whom? How could he be so sure someone—Paul—would look into the hacks? Would he have, if we hadn’t got to him?” Walker pulled the truck to a stop a block from the motel and parked around the corner. When he killed the engine, Monica was still silent, so he said, “Our next step is to find the book he used to crack it. The exact edition, right?”
“Yes.”
“And you have no idea what book he’d use.”
“No. He never did book ciphers with me.”
“Just with your father?”
“No. Not since . . . not for a long time.”
“Then who?”
“Paul. He used to do them with Paul.”