Before she became a wife, mother, and co-founder of Sanctuary, Nandi Monroe was a young lieutenant, engineer, and mech pilot in the United Colonies Militia's first Advanced Mech Division. During her first deployment into the war-torn megacity of White Run, she is thrown into brutal urban warfare where survival depends on courage, intelligence, and the machine she helped create: Morningstar. As war consumes the city around her, Nandi discovers the legend she is destined to become.