Jerin is at home with his sisters, from a few years old to much younger, when they hear gunfire and learn that there is an unconscious young woman on their land. On Jerin's insistence, they recover her, only to find soldiers want to recover her. Fortunately, the soldiers agree to hold off until the Queens Justice arrives to talk. Very fortunately, since, they learn, the woman is in fact the Princess Odelia. And the leader of the soldiers is the Princess Ren. (They had been looking for stolen cannon. The princess took precedence.)
And so the story heads off into adventure, romance, and intrigue in a very detailed world. One in which the sex roles are just about perfectly reversed. I particularly admire the world-building there because so many writers just do it as if it were that simple. Spencer has noticed that there are one or two biological differences between males and females that are reflected in society and worked out reasons why these difference nevertheless do not produce these reflections in the fictional society. I like how it works.