n ashen technician ran to the podium. “Tunnel block’s about to go!”

Jabba turned to the VR on screen. 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.