Boston, 1891. Sophia Tims comes from a family of explorers and cartologers who, for generations, have been traveling and mapping the New World—a world changed by the Great Disruption of 1799, when all the continents were flung into different time periods. Eight years ago, Sophia's parents left her with her uncle Shadrack, the foremost cartologer in Boston, and went on an urgent mission. They never returned.
Then Shadrack is kidnapped. Sophia must search for him with the help of Theo, a refugee from the West. Together they travel over rough terrain and uncharted ocean, encounter pirates and traders, and rely on a combination of Shadrack’s maps, common sense, and Sophia's unusual powers of observation. Little do they know that their lives are in as much danger as Shadrack's.