In the mid-19th century, a mute woman named Ada is sent away from her native Scotland to a rugged and remote part of New Zealand for an arranged marriage to a local colonist named Alisdair Stewart. Due to Ada's muteness from a young age, she expresses herself through her passionate piano playing and through sign language, which her young daughter, Flora, interprets for others. Ada brings her beloved piano with her, but Alisdair sees it as cumbersome and abandons it on the beach, symbolically stripping Ada of her voice. Isolated by geography and a loveless marriage, Ada is left to navigate her new life in a colonial wilderness filled with intruding European customs.

When a neighbor, George Baines, takes interest in the piano, he strikes a deal with Alisdair, taking possession of the instrument. In exchange for giving Ada private piano lessons, Baines proposes a series of increasingly intimate arrangements, allowing Ada to earn back her piano key by key. Despite the transactional nature of their agreement, Ada and Baines develop an unexpected connection. The complex emotional entanglements of this relationship reveal the stark contrast between passion and propriety. Ada's struggle to reclaim her piano becomes a metaphor for her search for self-expression in a society that seeks to silence her.