The novel tells the story of the friendship between two girls in late 19th-century China: Pearl Sydenstricker, the daughter of American missionaries, and Willow Yee, a poor Chinese girl. Despite their different social and cultural backgrounds, they form a strong bond.
Their lives are deeply affected by major historical events such as the Boxer Rebellion, civil wars, and the rise of communism in China. Pearl eventually leaves China to study abroad and becomes a famous writer, while Willow stays behind and faces poverty and political hardship.
Through memories and letters, the story explores how their friendship survives distance, time, and political change.