Catherine: The Great Journey — Kristiana Gregory

Fourteen-year-old Prussian princess Sophia finds herself entangled in her mother's efforts to arrange a marriage between Sophia and Charles-Peter, a young German duke and nephew of the Russian empress Elizabeth. As Sophia's mother moves to make the match, she and Sophia must travel from their humble home in Zerbst, Prussia, to Russia--the kingdom of Elizabeth. There, Sophia is renamed Catherine and married to Charles-Peter, but she watches helplessly as her family is torn from her, her own mother is involved in a spying ring against the empress, and all that is familiar to her disappears.