Law professor Natalie Greco has an ordered life. She feels a passion for teaching, especially her arcane seminar on the History of Justice, even though the course is pathetically undersubscribed in the high-powered law school. She has an attentive boyfriend and a protective family, although her testosterone-fuelled big brothers and very successful parents tend to overlook the quiet Nat. Then one terrible day, everything changes. Nat accompanies her colleague Angus to a prison in Chester County where he's a guest lecturer. It's a nice day for a drive through the countryside, the site for much Underground Railroad activity during the Civil War. However, the trip turns grim when they arrive at the prison, hardly inside before the speaker system announces a "disturbance" and orders a lockdown. They're smack in the middle of a riot. In front of a horrified Nat, a prison guard is fatally injured. Nat rushes to help him, only to hear his last words: "Tell my wife. It's under the floor. The money." At that moment, reinforcements arrive, the riot is quelled, and Nat and Angus are escorted out of the building by U.S. marshals. Remembering the dying guard's words, Nat feels she must find his widow. But this is no simple quest, and along the way, Nat is framed for murder and the retiring scholar finds herself in a desperate fight to save her own life.