Rain on the Red Flag details Thanh's remarkable journey, which begins on the day the Communists planted their flag in homes along his street in Saigon. Thanh's only chance of survival was to escape. During several escape attempts Thanh discovered parts of his country and its people that weren't known to him before. Later, Thanh was captured by the undercover police. For four years, he was held in jails and labor camps, chained, and starved. Only his love for freedom, music, the memory of his girl, his family, and friendship with the other prisoners keeps him sane.

When Thanh was finally set free and returned to Saigon, he helped to build a boat. He finds himself captaining the boat to navigate himself and seventy-five other refugees through tumultuous seas to seek freedom again.