It helps to have read Spence to understand the chaotic political situation in the 1920s and 1930s, up to and including the Japanese invasion. But China is just the background, not the subject of the story. Here we have an author born in Japan and raised in England, writing about an English boy who grew up in Shanghai, went to school in England, and then returned to China to solve the mystery of his parents' disappearance. An amazing story, masterfully told. A double story unfolds.
History unfolds in the background as personal mysteries and dramas are unravelled.
You feel like you were there and lived through it. You come to accept and take for granted beliefs and values that at first seemed incomprehensible. You remember the story and the history surrounding it as experienced rather than explained.