There's something sinister lurking in the waves. It's 1921 in Widow's Peak, a gloomy fishing village on the south coast of New South Wales. Nineteen-year-old Missy Green fills her days helping her fisherman father on his trawler. It's a dreary existence. Everything in her sea salt-soaked life is upended, though, when she glimpses something in the water - a mermaid ominously staring at her. When Missy discovers a mutilated woman washed up on shore, her disturbing hallucinations of the mermaid gather steam. Missy must navigate the treacherous waters of her secret-filled community - and attempt not to drown in the recesses of her mind, and the eyes of a handsome detective.