The study aims to investigate the use sound and music in Christopher Nolan’s 2017 film Dunkirk and how it works as agent to tell the story. The theoretical approach consists of Narrative theory, Charles S. Peirce’s Semiotics approach, Connotative and denotative Cognition function and narrative theory to various aspects of film sound. Result shows that the sound and music functions as the agent of Narrative as it helps viewer to understand the emotional and psychological state of the character; as well as enhance the visual to emphasize the feeling and intensity of a specific scene or character's emotional state.