On an isolated cattle farm, a couple experimenting with biotechnology have their lives upended when they discover a disturbing presence on their property.

After 16-year-old Alice Palmer drowns at a local dam, her family experiences a series of strange, inexplicable events centered in and around their home. Unsettled, the Palmers seek the help of a psychic and parapsychologist, who discovers that Alice led a secret, double life. At Lake Mungo, Alice's secret past emerges.