In order for a user to use Wi-Fi, the bouncer had to trust the user and open a port for him or her. Once trust was established, anything the user sent through that port was also trusted. That was because the library network had its own firewall and most users relied on default settings when setting up their computers, and default settings tended to be far too trusting where Wi-Fi networks were concerned. Bad idea in general. Really bad idea in this case, since Gibson’s program was already inside the library’s firewall.

As a result, Gibson’s program would allow him to wander in unaccosted and gather information from most computers logged in to the library Wi-Fi. Depending on the computers’ individual security settings, he might gather names, addresses, contacts, cell numbers, credit-card numbers, and outgoing IP addresses—all in a matter of seconds.

In addition, by exploiting the Wi-Fi access points scattered around the library, he could more or less triangulate users’ locations. Unfortunately, there weren’t enough access points to give more than a crude map, but he could tell at a glance how many users were on each floor of the library, how many in the park to the west, and if anyone was on one of the side streets within range.

As he stood to leave for Jenn’s six thirty a.m. briefing, one of his monitors flashed an alert. It showed a solitary log-in coming from the park. Immediately, personal data from the device began to unspool across another monitor: Lisa Davis . . . 814 area code . . . home address . . . work address . . . e-mail . . . contacts . . . web-browser history. He smiled and toggled over to the cameras in the park. No one on a laptop; the only person in the park was a pregnant woman pushing a stroller.

Probably meant her smartphone was connecting automatically to the library network. To be certain, he dialed her number, and then on the camera monitor watched her take out her phone and, not recognizing the incoming number, send him straight to voice mail.

Sure enough, a pedestrian at the far edge of the Wi-Fi’s range connected to the network for a few seconds before passing out of range. It popped up as a blip on his map and then vanished just as quickly.

Gibson frowned. Smartphones would make things messy. It was an obvious enough issue that he kicked himself for not anticipating it. Times had changed since his arrest, and he needed to catch up quickly. He was glad neither Jenn nor Hendricks was here to call him out for it.