The story is based on Summerset Maugham's novel of the same name.
A British couple leaves London and arrives in Shanghai, then leaves Shanghai and travels to the interior of China. Their marriage is not happy. He started out loving her while she did not love him. She has an affair. He finds out and manipulates her into joining him when he volunteers to work in a cholera epidemic amidst political upheaval. She is a vain and shallow girl who grows during the movie. It isn't until the very end that they finally begin to respect and love each other.
I liked The Painted Veil more before I read the NY Times Review. The reviewer was unhappy that the story took liberties with the novel, and presented the husband as a more vibrant character than he was in the book.