Miri is a fourteen-year-old girl from Mount Eskel, an isolated territory of Danland, who has never been allowed to work with the rest of the villagers in the quarry that keeps the community alive. The quarry workers cut linder, which they sell to the lowlander traders. Because of this, she feels like an outcast in the community and cut off from the culture focused around a shared working life in the quarry. As the quarry can barely cut enough linder to feed the villagers, Miri keeps on trying to help. In spite of her feelings of isolation, Miri is very close to her father and her sister, Marda, and she shares a close friendship with a boy named Peder.
Unexpectedly, a messenger from the king arrives along with the usual traders from the lowlands. The messenger announces that the nation's priests have informed the nation that, despite the lack of education provided for the villagers and the prejudice that exists between the mountain villagers and the lowlanders, the crown prince's future bride will come from Mount Eskel.
A "princess academy" is established near the village to train the potential princesses, with compulsory attendance for every girl aged from twelve to eighteen. At the end of the year, the prince will visit the academy and choose the girl to be the next princess.
Miri and the other girls attend the academy, and although they struggle to appease the strict teacher, Tutor Olana, Miri excels at learning and commerce. All the girls are eager to please the prince and win a comfortable life for themselves and their families, and Miri's new knowledge of commerce helps the village prosper in trading with the lowlanders. After a disagreement, the girls use their knowledge of diplomacy to negotiate a more bearable living arrangement with Tutor Olana, including weekly visits home. Miri also begins to explore the mechanics of quarry-speech, a form of unspoken communication used only in the quarry, and makes friends with some of the other girls, including Britta, a lowlander who had recently moved to Mount Eskel.
Miri's excellence in her studies and her willingness to help her peers despite bitter competition eventually earn her the title of academy princess and the privilege of having the first dance with the prince. At the academy ball, the prince dances with every girl except Britta, who is ill, and generally acts very distant. Later in the evening, he takes a walk with Miri and shows a more human side. However, he leaves without choosing a bride. Once the prince has left, promising to return in the spring to announce his choice, bandits attack the academy hoping to hold the new princess hostage. Miri must use her new knowledge of quarry speech to call for help from the village. At first no one seems to hear her, but eventually she is able to contact Peder. The villagers come to the academy through the blizzard, and the girls escape from the bandits and spend the winter at home with their families. In the spring, the prince returns and chooses to marry Britta - whom he has known since childhood - and names Mount Eskel an official province. The book ends with Peder and Miri admitting their feelings toward each other.