On the eve of the 60's feminist movement, just before Vatican II, Kate Mahoney was Sister Katherine. Twenty years later, as the widowed principal of an elementary school in a crime-riddled neighborhood, she is vexed when a deceased Mother Provincial invades her dreams and orders her to solve a murder that occurs in her first grade classroom. As the body count grows, Kate teams up with the unlikely new School Resource Officer, Theo Buloski, to solve the murders and get the first grade teacher, Elijah Stewart, out of jail. When Kate's life is threatened, Mother Provincial's wise clues pay off. All the while, Kate and Theo continue protecting the children from the usual inner-city threats, which are scary enough without the additional bloodshed.