In the year 2131, a colony has been established on a planet named 'Heaven'. Two sisters, Rhian and Seren, have ventured there in the hope of starting new lives away from the war, disease and poverty of Earth. Not long after their arrival, it becomes apparent that conditions on the planet are dangerously harsh. With Seren's health failing fast, Rhian grows desperate to save her at any cost. When a sinister alien sea creature begins communicating with Rhian, it presents her a chance of survival but at a terrifying cost.