Native Speaker is a novel told from the perspective of Henry Park who is a first generation Korean American. Henry has reached a point when he has begun to reconsider everything of significance in his life, including thoughts on his parents' way of life, his career, and his worth as a spouse. The novel opens when Henry's wife is leaving on a vacation. This is her vacation away from Henry.

At the airport before boarding her plane, Henry's wife, Leila, gives him a list to read after she is gone. It is a list of traits and behaviors of Henry that she has complied over time. Nothing on the list is flattering and much of it is insulting. Henry reads the list over and over while she is away.

Henry's professional life is also suffering. He has begun to question the morality of what he does for a living. Henry is a spy but he is not in the employment of the government. He works for a company that will gather information on anyone for a price. Henry's particular company specializes in gathering information on immigrants and they do this by employing people of many different races. Henry's area of specialty includes people from Asian cultures. Previously a model employee, Henry currently experiences difficulty at work because he performed poorly on his last assignment and caused his company to lose a large amount of revenue.

Throughout Henry's journeys in life, he always weighs events and ideas against the ideals of his father. Henry's father died years before the opening of the novel, but he plays such an important part in Henry's perception of events that he is real and feels very much like a main character. Henry and his father did not have a relationship free of troubles however. Henry's mother died when Henry was only ten years old and Henry who knew nothing of Korean culture beyond what he learned from his parents, often clashed with his father's more traditional ideas. As Henry ages and acquires more wisdom, he begins to reevaluate his estimation of his father.

Henry must balance the calamity in his personal life with a new and challenging assignment at work. He is assigned to gather information on John Kwang, a rising Korean American politician. Henry finds that he has a personal affinity for Kwang and a deep admiration of Kwang's goals. This leads to Henry questioning whether he is making a living by betraying his own people. Soon he finds that he is keeping secrets not only from his wife and the politician he is sent to investigate, but he is also withholding information from his employer. Somehow Henry must find a way to satisfy all parties.

Throughout the novel, Henry struggles with questions that we all face regardless of age, race, or gender. Henry wonders about personal identity. His job requires him to adopt many different identities, but in time Henry comes to recognize that we all have multiple identities, and Henry is not sure which one is the true Henry. He cannot be sure which of his many identities is his true self and he cannot be certain which of the many identities others present to him are legitimate people. Henry must find these answers while he struggles to repair his marriage and put to rest some old misguided grievances against his father.