The Lover by Marguerite Duras

Set against the backdrop of French Indochina, The Lover reveals the intimacies and intricacies of a clandestine romance between a pubescent girl from a financially strapped French family and an older, wealthy Chinese-Vietnamese man.
In 1929, a 15-year-old nameless girl is traveling by ferry across the Mekong Delta, returning from a holiday at her family home in the town of Sa Đéc to her boarding school in Saigon. She attracts the attention of a 27-year-old son of a Chinese business magnate, a young man of wealth and heir to a fortune. He strikes up a conversation with the girl; she accepts a ride back to town in his chauffeured limousine.

Source: Wikipedia