The Zero Hour

Then he wrote out a message, which began: LEAK YOUR END. AMERICAN INTELLIGENCE PARTIALLY KNOWLEDGEABLE. THOROUGHLY SWEEP HOME, OFFICES, COMMUNICATIONS EQUIPMENT, CHECK PERSONNEL. DON’T USE TELEPHONE. I WILL BE OUT OF CONTACT. He ended it: HEREBY ACKNOWLEDGE RECEIPT SECOND PAYMENT.

Using the red-plastic-bound Webster’s pocket dictionary he’d bought in Paris, a twin of which Dyson had, he encrypted the message by means of a simple substitution cipher and typed it out on one of the preprinted forms. The text appeared to be an authentic-looking invoice requesting prices on a list of things-item #101.15, item #13.03, and on and on. Dyson alone knew this referred to page 101 in the dictionary, fifteen major words down on the page, etc. This simple cipher was almost unbreakable.

Baumann had set a five-minute window for Dyson to fax a similarly encoded reply. He ordered a room-service lunch, took a brief nap, and once again set up the MLink-5000.

Precisely as the five-minute window began, his SATCOM blinked to indicate an incoming signal, then the fax machine warbled and out came Dyson’s reply.

He read it, and then, in the glass ashtray, burned it and all the other pieces of paper he had used. He flushed the ashes down the toilet, then went out for a stroll.

***

Christine Vigiani had been tasked to be liaison with the National Security Agency. In reality, this meant one thing only: find out whatever she could about the intercepted telephone conversation, and urge them to get more. Sarah had arranged to have her cleared at a high enough level to read the NSA telephone intercept.

Not only is the NSA notoriously secretive, but it is disinclined to share with rival agencies more than it absolutely must about its sources and methods. Vigiani was having a hell of a time finding anyone at NSA who knew what he was talking about and had the authority, or the willingness, to talk.

Finally, an NSA analyst named Lindsay called Vigiani on the STU-III secure phone. He was cordial and seemed familiar with the satellite intercept in question.

“The first thing we need to know,” Vigiani said, “is whether you captured the telephone numbers of the caller or the recipient along with the conversation.”

“No.”

“You didn’t? You’re sure of that.”

“Right. The answer is no, we did not.”

“Neither one. Neither sender nor receiver.”

“Correct.”

“Why not?”

Lindsay paused. “How to answer that,” he sighed. “What we got was a snatch of conversation in midstream, so to speak. A few minutes from somewhere in the middle of the phone call.”

“But the satellite intercept-” Vigiani said, not sure of what she was saying.

Lindsay sensed her ignorance and responded in simple language: “It’s actually rare to get the phone number that’s being called,” he said. “Pure happenstance. We’d have to have locked on to the call from the very first second, so we could hear the dialing or the touch tones being punched.”

“It’s really that crude?”

“It’s what the technology allows.”

“Well, what we’d like is for you to have your satellites search for this same encryption scheme again. We figure that whoever made this call will continue to use this encrypted phone, and so now that we know the key, we can just pick up anything in the ether with that configuration, or whatever.”

“Doesn’t work that way,” Lindsay said. “Our satellites can’t tell any particular encryption scheme is being used until the signal is down-linked and examined.”

“You’ve got to be kidding me. Am I talking to the National Security Agency?”

Lindsay’s response was cold silence.

“All right,” Vigiani said, “what do you know about this intercept?”

“We know a number of things. We know it was a digital signal, to start with, which is helpful, because there aren’t that many digital phone signals out there in the ether yet. Soon, that’s all there will be. But not yet.”

“What else?”

“And we know which microwave relay station the signal was captured from, its exact location. It’s the Geneva North microwave relay, numbered Alpha 3021, located on a mountain north of Geneva. If our caller uses this phone again, the signal will likely be transmitted using the same relay. We can target that station.”

“Okay…”

“Also, each microwave relay station uses a known, fixed set of frequencies. We can tell our receiving station to listen in on these frequencies, scan them. Of course, we’ll ask the British, GCHQ, to monitor the same frequencies and process them. If we’re really lucky, we’ll record another signal that won’t decrypt.”

“Fine,” Vigiani said, “but this time get the phone number, okay?”

“Okay, right,” the NSA man said dryly. “You got it. Whatever you want.”

Vigiani got up from her desk and walked toward Sarah’s office. There, gathered around Sarah in a knot, were most of the task force members watching Sarah speak on the phone. Everyone, including Sarah, looked stricken.

“What?” she said to Ullman. “What is it?”

“It’s Duke,” he said without even turning to her.

CHAPTER FORTY-SEVEN