The warm fall day starts like any other at the Center, a women's reproductive health services clinic, its staff offering care to anyone who passes through its doors. Then, in late morning, a desperate and distraught gunman bursts in and opens fire, taking all inside hostage. After rushing to the scene, Hugh McElroy, a police hostage negotiator, sets up a perimeter and begins making a plan to communicate with the gunman. As his phone vibrates with...