In her forties, with two children, a spouse, a dog, a mortgage, and a full-time job as a tenured law professor at Georgetown University, Rosa Brooks decided to become a cop. A liberal academic and journalist with an enduring interest in law's troubled relationship with violence, Brooks wanted the kind of insider experience that would help her understand how police officers make sense of their world--and whether that world can be changed. In 2015, against the advice of everyone she knew, she applied to become a sworn, armed reserve police officer with the Washington, DC, Metropolitan Police Department. Then as now, police violence was constantly in the news. The Black Lives Matter movement was gaining momentum, protests wracked America's cities, and each day brought more stories of cruel, corrupt cops, police violence, and the racial disparities that mar our criminal justice system. Lines were being drawn, and people were taking sides. But as Brooks made her way through the police academy and began work as a patrol officer in the poorest, most crime-ridden neighborhoods of the nation's capital, she found a reality far more complex than the headlines suggested.