As Gurney was eyeing the black-clad figure and weighing this circumstantial evidence, the background strumming and twanging of country music that had filled the fairgrounds abruptly ceased—and was followed by several seconds of loud static and finally an announcement:

Ladies and gentlemen, may I have your attention, please. This is an emergency announcement. Please remain calm. This is an emergency announcement. We are currently responding to several fires of unknown origin. For everyone’s safety, we are discontinuing this evening’s scheduled events. We will be evacuating the fairgrounds in a safe and orderly fashion. Any rides now in progress will be the last ones this evening. We ask that all exhibitors begin closing down their booths and displays. We ask that everyone follow the instructions of security, fire, medical, and safety personnel. This is an emergency announcement. All fair visitors should begin proceeding in an orderly fashion toward the exits and the parking areas. I repeat, we are responding to several fires of unknown origin. For everyone’s safety at this time we must begin an orderly evacuation of the—

The announcement was truncated by the loudest explosion yet.

Panic was spreading widely. Shouts. Mothers screaming for their children. People looking around wildly, some struck motionless, some moving erratically.

Black Hoodie, standing at the rail, gazing up at the colossal Ferris wheel, showed no reaction at all. No shock, no curiosity. This, in Gurney’s estimation, was the most damning evidence so far. How could this person not react—unless what was happening was no surprise to him?

As was often the case in Gurney’s mental life, though, growing conviction brought with it a growing caution. He was all too aware of how one’s perceptions can start lining up to support a particular conclusion. Once a pattern begins to take shape, however erroneous it might be, the mind unconsciously favors any data points that support it and discounts any that don’t. The results can be disastrous and, particularly in law enforcement, fatal.

Suppose Black Hoodie was just another pathetic waster, stoned out of his mind, more absorbed by the carnival lights than by any real danger. Suppose he was just another one of a million people on the planet with a small hooked nose. Suppose the spattered mud on his pants had been there for the past week?

Suppose what seemed like an increasingly obvious pattern wasn’t a pattern at all?