Eighteen-year-old Robert Weekes is a practitioner of empirical philosophy – an arcane, female-dominated branch of science used to summon the wind, shape clouds of smoke, heal the injured, and even fly. Though he dreams of fighting in the Great War as the first male in the elite US Sigilry Corps Rescue and Evacuation Service – a team of flying medics – Robert is resigned to mixing batches of philosophical chemicals and keeping the books for the family business in rural Montana, where his mother, a former soldier and vigilante, aids the locals.