2019: Lucy awakens from a dream to find her hands around her ex-lover's throat. Horrified, she flees to her older sister's house on the Australian coast, hoping she can help explain the strangely vivid nightmare that preceded the attack, but Jess is nowhere to be found. As Lucy awaits her return, the rumors surrounding Jess's strange small town start to emerge. Numerous men have gone missing at sea, spread over decades. A tiny baby was found hidden in a cave. And sailors tell of hearing women's voices on the waves. Desperate for answers, Lucy finds and begins to read her sister's adolescent diary. 1999: Jess is a lonely sixteen-year-old in a rural town in the middle of the continent. Diagnosed with a rare allergy to water, she has always felt different, until her young, charming art teacher takes an interest in her drawings, seeing a power and maturity in them, and in her, that no one else has. 1800: Twin sisters Mary and Eliza have been torn from their loving father in Ireland and forced onto a convict ship bound for Australia. For their entire lives, they've feared the ocean, as their mother tragically drowned when they were just girls. Yet as the boat bears them further and further from all they know, they begin to notice changes in their bodies that they can't explain, and they feel the sea beginning to call to them.