The story of a heroic "war dog" whose skill and bravery saved countless lives during the Vietnam War. To honor the memory of her fallen brother, 9-year-old Amy Davis, with the help of her mother, decides to donate her beloved German shepherd, Rain, to be trained to fight alongside Army soldiers in Vietnam. After a teardul goodbye, Rain arrives at training camp where he meets his new master, Joe Holland. By the end of the 16 weeks of training, Rain and Holland have developed a deep bond and are ready for South Vietnam. Their arrival in Vietnam divides their platoon, with Captain Pike pleased to have this unique soldier, and Sergeants Crawford, Summers, Morris, Junior and Jordan scoffing at the four-legged fighter. The platoon's minds are changed when Rain saves them from a deadly trip wire and alerts them to the nearby enemy, thanks to his heightened sense of hearing.