A major plot element of a third book that I’m working on centers around critical infrastructure systems, like computers that control dams or power plants. Why do hackers want to get into these systems? First, these systems are extremely vulnerable. Many of the computers which control our power grid, airplane traffic, and nuclear power plants use outdated software that is rarely patched. Hackers are starting to recognize that these systems are easy targets. Second, and more importantly, hackers understand the chaos that can be caused by bringing down the power grid or turning off a water treatment plant. Stealing a credit card number only affects one person. But shutting down a major airport because none of the fight control systems work can affect millions of people.