The Grass King's Concubine is a descriptive fantasy, following the journey of wealthy Aude Pelerin des Puiz as she struggles to understand why some people in her nation are rich, while others are poor. As a young woman, she takes to wandering the streets of the dirty, dangerous Brass City, where she encounters and falls in love with Jehan Favre, a soldier who likewise questions the wealth inequities of their nation. Together, they travel to the original lands of Aude's family in order to discover the origins of her family's wealth.