At the end of the Vietnam War, American Captain Willard (Martin Singh Martin Sheen) is ordered up the Mekong River to search for Colonel Coates (Marlon Brando Marlon Brando), who has separated from the US military and established his own kingdom in Cambodia, bringing him back or killing him. Guru Coates was once a hero of the US military in the Vietnam War. However, suddenly one day, he disappeared. Subsequently, intelligence pointed out that he had established his own kingdom and his own army in Cambodia, specifically against the United States. Along the way up the river with several soldiers, Willard was shocked by the atrocities, killings, and abnormal behaviors committed by both American soldiers and locals during the long war. Willard was finally caught by locals in the kingdom of Coates in Cambodia and met Coates. However, Coates wanted to die and asked Willard to blow this place to the ground.