In October1968 Captain George Morgan is about to embark on what he considers to be the best job in the U.S. Army commanding a rifle company in combat. At age 27, he will be referred to as "The Old Man" by the soldiers under his command. He is already a seasoned veteran of service in Vietnam and is now returning for a second tour of duty in what has become an increasingly unpopular war in the U.S. During this assignment, Morgan acquires a keen sense of responsibility to his unit, which calls itself "Charlie Hunter", and to the men who serve in it. He develops a special bond with many of his men, and one in particular a young Mexican who is nicknamed Mouse. The story takes this unit on many dangerous missions and recounts the bravery and compassion of the soldier called Mouse. In the course of operations, the unit comes into contact with a mysterious Vietnamese woman, who eventually brings the commander to Saigon. That visit draws the captain into the realm of espionage and subterfuge and culminates with him on stand-by to lead a mission to rescue the Vietnamese woman. While leading his men on combat missions, Captain Morgan becomes increasingly disillusioned with the war and finds it more and more difficult to justify America's presence in Vietnam to his subordinates; yet, he must continue to set the example and project the image of the "stalwart commander."