Digital Fortress

"Put in the spaces," Susan ordered. "We've got a puzzle to solve."

Chapter 123

An ashen technician ran to the podium. "Tunnel block's about to go!"

Jabba turned to the VR onscreen. The attackers surged forward, only a whisker away from their assault on the fifth and final wall. The databank was running out of time.

Susan blocked out the chaos around her. She read Tankado's bizarre message over and over.

PRIME DIFFERENCE BETWEEN ELEMENTS RESPONSIBLE FOR HIROSHIMA AND NAGASAKI

"It's not even a question!" Brinkerhoff cried. "How can it have an answer?"

"We need a number," Jabba reminded. "The kill-code is numeric."

"Silence," Fontaine said evenly. He turned and addressed Susan. "Ms. Fletcher, you've gotten us this far. I need your best guess."

Susan took a deep breath. "The kill-code entry field accepts numerics only. My guess is that this is some sort of clue as to the correct number. The text mentions Hiroshima and Nagasaki-the two cities that were hit by atomic bombs. Maybe the kill-code is related to the number of casualties, the estimated dollars of damage…" She paused a moment, rereading the clue. "The word 'difference' seems important. The prime difference between Nagasaki and Hiroshima. Apparently Tankado felt the two incidents differed somehow."

Fontaine's expression did not change. Nonetheless, hope was fading fast. It seemed the political backdrops surrounding the two most devastating blasts in history needed to be analyzed, compared, and translated into some magic number… and all within the next five minutes.

Chapter 124

"Final shield under attack!"

On the VR, the PEM authorization programming was now being consumed. Black, penetrating lines engulfed the final protective shield and began forcing their way toward its core.

Prowling hackers were now appearing from all over the world. The number was doubling almost every minute. Before long, anyone with a computer-foreign spies, radicals, terrorists-would have access to all of the U.S. government's classified information.

As technicians tried vainly to sever power, the assembly on the podium studied the message. Even David and the two NSA agents were trying to crack the code from their van in Spain.

PRIME DIFFERENCE BETWEEN ELEMENTS RESPONSIBLE FORHIROSHIMA AND NAGASAKI

Soshi thought aloud. "The elements responsible for Hiroshima and Nagasaki… Pearl Harbor? Hirohito's refusal to…"

"We need a number," Jabba repeated, "not political theories. We're talking mathematics-not history!"

Soshi fell silent.

"How about payloads?" Brinkerhoff offered. "Casualties? Dollars damage?"

"We're looking for an exact figure," Susan reminded. "Damage estimates vary." She stared up at the message. "The elements responsible…"

Three thousand miles away, David Becker's eyes flew open. "Elements!" he declared. "We're talking math, not history!"

All heads turned toward the satellite screen.

"Tankado's playing word games!" Becker spouted. "The word 'elements' has multiple meanings!"

"Spit it out, Mr. Becker," Fontaine snapped.

"He's talking about chemical elements-not sociopolitical ones!"

Becker's announcement met blank looks.

"Elements!" he prompted. "The periodic table! Chemical elements! Didn't any of you see the movie Fat Man and Little Boy-about the Manhattan Project? The two atomic bombs were different. They used different fuel-different elements!"

Soshi clapped her hands. "Yes! He's right! I read that! The two bombs used different fuels! One used uranium and one used plutonium! Two different elements!"

A hush swept across the room.

"Uranium and plutonium!" Jabba exclaimed, suddenly hopeful. "The clue asks for the difference between the two elements!" He spun to his army of workers. "The difference between uranium and plutonium! Who knows what it is?"

Blank stares all around.

"Come on!" Jabba said. "Didn't you kids go to college? Somebody! Anybody! I need the difference between plutonium and uranium!"

No response.

Susan turned to Soshi. "I need access to the Web. Is there a browser here?"

Soshi nodded. "Netscape's sweetest."

Susan grabbed her hand. "Come on. We're going surfing."

Chapter 125

"How much time?" Jabba demanded from the podium.

There was no response from the technicians in the back. They stood riveted, staring up at the VR. The final shield was getting dangerously thin.

Nearby, Susan and Soshi pored over the results of their Web search. "Outlaw Labs?" Susan asked. "Who are they?"

Soshi shrugged. "You want me to open it?"

"Damn right," she said. "Six hundred forty-seven text references to uranium, plutonium, and atomic bombs. Sounds like our best bet."

Soshi opened the link. A disclaimer appeared.

The information contained in this file is strictly for academic use only. Any layperson attempting to construct any of the devices described runs the risk of radiation poisoning and/or self-explosion.

"Self-explosion?" Soshi said. "Jesus."

"Search it," Fontaine snapped over his shoulder. "Let's see what we've got."