The story was set during World War II when the Japanese Empire sent troops to Siam (Thailand) as part of their greater plan. Kobori, an idealistic Japanese officer set up a base camp by the Chaophraya River which is in the area of Angsumalin‘s house. He falls for her at first sight. Angsumalin, a proud Thai who despises every kind of threat to her country, sees him as a part of the Japanese Empire that deserves only hatreds. Despite his duty, Kobori wants to believe that his love will be able to find its way into her heart.

Angsumalin, the beautiful daughter of a military leader, says good-bye to her friend Vanus, who is going to England to study. She won't promise to marry him, but will give him an answer when he returns. The Japanese invade, and circumstances bring Angsumalin together with Kobori, an idealistic Japanese captain, who is also related to a powerful Japanese general.

The story of endless love is set amidst the fiercest conflict this world has ever known – World War II. As war is about to break out in Europe, Vanus is on his way to England to join the Free Thai movement. He hopes to receive a definite promise from Angsumalin that she will marry him after the war.

Set in 1939, the early days of World War II in Siam, to Angsumalin meeting one last time with her childhood friend, a young Thai man named Vanus. He is leaving for England for his studies and hopes that Angsumalin will wait for him and marry him when he returns.

A love story between Thai woman and Japanese soldier during Japanese invasion.

Koburi the Japanese Army Officer portrayed in Sunset at Chaopraya's earlier films dies and the film then goes on to the future of his child and his life which leads to be a leader in the 1973 student riots in Thailand which turned into a massacre.