“Okay. Let’s say the head of Saudi Intelligence calls Bashir Isa to give him instructions,” Ward said, writing HSI on one side of the mat and then drawing a line to a point where he wrote BI. “Then Bashir Isa calls Muhammad Singh.” He drew another line, this time from the BI to a point where he wrote MS. “Then Singh calls Auma. Then Auma fails to kill David and he calls back to Singh, who then reports that to Isa. Who, in turn, reports back to the head of Saudi intelligence.” With each thread, he drew another connecting line. “Then the head of Saudi intelligence uses the same burner phone to call your mole for information on me.” He drew a line to a point where he wrote mole. “Obviously, this chain is hypothetical. There might be more actors, but you get the idea.”

“Not really,” Rapp said, looking down at the spiderweb of connections. “All you have there is a bunch of anonymous phones calling other anonymous phones. No names.”

“Correct. All we know is what phone called what phone at what time and what cell tower they were connected to at the time of that call.”

“So, we’re a little better off. We have a general location of the phones at the times the calls were made because of the tower connection. But that’s still a long way from putting owners to them.”

“Not as far as you might think, Mitch. Let me ask you a question: When you use a burner, is your regular cell phone in your pocket?”

“Usually.”

“And is it turned on?”

“Probably,” he said, starting to get a glimmer of where Ward was going with this.

“Okay. Let’s say your mole made or received five calls to our nefarious little group here. And—using a best-case scenario—he’s done so from five different places. Like I said before, we know the time of those calls and the cell tower he was connected to when they were made. Do you see his problem?”

Shit. Rapp actually could see the problem. And now it made him think back on every burner call he’d made since the invention of the smartphone.

“All you have to do is figure out what cell phones were communicating with those towers at the same time.”