Set in the 1950s and 60s, the film tells the story of Kya Clark, a young girl abandoned by her family and left to raise herself in the marshes of North Carolina. Known as the "Marsh Girl" by the townspeople, Kya leads an isolated life, finding solace and understanding through her studies of the natural world. Despite her loneliness, she forms two significant connections: one with Tate Walker, a kind and intelligent boy who teaches her to read and fuels her deepening love for knowledge, and another with Chase Andrews, the local wealthy and charming playboy. As Kya grows up, these relationships shape her world, but she remains constantly wary of those who misunderstand her unique way of life.

The narrative takes a dramatic turn when Chase Andrews is found dead, and Kya becomes ensnared in a murder investigation. Her reclusive nature and mysterious background make her an easy target for suspicion, and the community's bias against her fuels the proceedings. As Kya navigates the complexities of human connections and the prejudices of society, she must also unravel the mystery surrounding Chase's death. The film interweaves themes of survival, prejudice, love, and resilience as it shifts back and forth in time, gradually revealing layers of Kya's character and her struggle to find her place in a world that is quick to judge what it doesn’t understand.