The Zero Hour

Sarah stared. “How much?”

“A thousand pounds.”

“Holy shit,” she said.

***

“So what you’re telling me,” Assistant Director Joseph Walsh sputtered, “is that you don’t know crap.”

“No, sir,” the FBI explosives analyst replied, coughing nervously into a loose fist. “I’m telling you we can only ascertain broad generalities.”

Walsh was intimidating enough in manner. He did not need to plant his burly six-foot-seven-inch frame next to the diminutive explosives expert, towering over him, as he was doing now. Sarah and Harry Whitman, the chief of the Joint Terrorist Task Force, watched the interplay with grim fascination.

“Jesus Christ,” Walsh thundered. “We have the fucking fusing mechanism. We know a thousand pounds of C-4 has been stolen. What else do you want? A blueprint and a wiring diagram? A guided fucking tour?”

But the explosives expert, a small and precise man named Cameron Crowley with a graying crew cut and a pinched pink face, was not put off quite so easily. He had done excellent work after the World Trade Center bomb and Oklahoma City, and everyone in Walsh’s office knew it. On reputation alone he could coast. “Let me tell you exactly what we do know,” he said, “and what we don’t know. We know a thousand pounds of C-4 may-I repeat, may-be part of this bomb. We don’t know if the theft of this plastic is a coincidence, or whether it was done by, uh, Baumann.”

“Fair enough,” Sarah put in to encourage the man.

“But assuming Baumann stole it, we don’t know if he’s planning one bomb or a series of bombs. We don’t know if he’s planning to use all of the thousand pounds in one bomb. That’s a hell of a lot of explosive power.”

“What’s a ‘hell of a lot’?” asked Walsh, as he pivoted to return to his desk.

The expert sighed with frustration. “Well, don’t forget, it only took one pound of plastic to bring down Pan Am 103. Four hundred grams, actually. A thousand pounds can certainly do a lot more damage than was done in TRADEBOM. That wasn’t even dynamite-it was a witches’ brew of ammonium nitrate and all sorts of other stuff-but it blew out a six-story hole in the tower. It had an explosive force equivalent to over a thousand pounds of TNT.”

He explained that on the table of relative destructiveness as an air-blast explosive, TNT is 1.0, ammonium nitrate is.42, dynamite can be anywhere from.6 to.9, and C-4, Semtex, and British PE-4 all have a value of 1.3 or 1.35. “So,” he concluded, “weight for weight, C-4 is about a third more powerful than TNT.”

“Can it bring down a building?” Walsh asked impatiently.

“Yes. Some buildings yes, some no. Not a huge building like the World Trade Center.” He knew there had been four studies done on the engineering aspects of the World Trade Center complex, which determined based on vibration analysis that the World Trade Center buildings could not be knocked down by any bomb short of a nuke. “In any case, it depends on a whole lot of factors.”

“Such as?” Whitman prompted.

“Location of the bomb, for one thing. Is it going to be placed outside or inside the building? Most bombs are placed outside buildings so that the damage will be visible, easily seen and photographed, for maximum psychological impact.”

“If it’s placed inside the building…?” Sarah asked.

“The rule of thumb is that a bomb confined inside a building will do five times more damage than one placed outside. Then again, look what happened in Oklahoma City.”

“You’re still not telling us anything!” Walsh shouted.

Sarah could see Cameron Crowley compress his lips to contain his irritation. “Blast analysis is a complicated business,” he said quietly. “The geometry of the charge has some effect on the peak pressure of the shock wave that emanates from the explosive. The shock waves always move at a ninety-degree angle to the surface of the explosives. We don’t know if the charge is going to be shaped, or spherical, or what. Is there any way for the explosive to vent and thus be diffused? Also, we don’t know what building it’s going to be placed into. Different substances have different abilities to withstand the shock front. Glass generally yields between one and three p.s.i. when hit with a front-on load. A typical masonry wall-a good, well-made brick wall-will break at eight to twelve p.s.i. And if there’s steel reinforcing, well, steel has a modulus of elasticity, called Young’s modulus-”

“Goddammit,” Walsh said. He was not a thick or ignorant man, far from it, but he was famously impatient with scientific bluster that served in his opinion to muffle practicalities. “What you’re saying is that a thousand pounds of C-4, if placed intelligently inside a reasonably sized Manhattan office building, can do a fuck of a lot of damage.”

“Yes, sir,” Crowley said. “A fuck of a lot.”

The intercom on the AD’s desk buzzed. Walsh lumbered over to it, hit the switch, and said: “Dammit, Marlene, I said hold all calls.”

“Sorry, sir, but it’s urgent, for Agent Cahill.”

“Oh, for Pete’s sake. Cahill?”