“Come on, let’s think. We may be wrong, but what is, if it were you, what is the worst-case scenario? Where would you go to do the most damage, inflict the most harm?”

“You’re thinking, start from the worst, and work our way towards the most likely?”

“Something like that.”

Their conversation came to an abrupt halt, as the sound of a very large concussion filled the air. Two seconds later, Billy thought he saw the evergreen trees around them start waving in the wind, ever so slightly. None of the dead leafy trees seemed to notice anything, but two young men walking up the street in the opposite direction were looking and started pointing to the southwest. At the crest of the next hill, Billy and Ally could clearly see smoke rising from the base of Green Mountain, a landmark hill to the west of Denver.

“Holy shit,” they said together.

“Dammit, I hate it when you’re right,” she continued, though, by her tone of voice, she wasn’t even amused by her statement.

“Yeah, me too.”

They rode on in silence for several blocks before she snapped out of it.

“Well, now we know there’s going to be something.”

“Yeah.”

“So, what’s it gonna be? What is that worst-case scenario? Think.”

“Okay.” Billy rubbed his neck for a moment, thinking. Suddenly, his face twisted, scared.

“What,” Ally asked.

“Well, there’s about to be . . . “

“Seventy-eight thousand people exiting a single building all at . . .”

“. . . at the same time.”

They looked at each other for a second, then turned their attention elsewhere. Billy, to the road, which he accelerated down at a reckless pace. “Okay. Here we go.”

Billy veered off of Sheridan Street and onto Colfax Avenue, headed straight into downtown Denver. He glanced down at the clock.

4:45.