There's something in the water, preying on men, women, children and animals along the UK coastline. For two years, Simon, a teenager, has been tasked with providing live bodies for the thing. Like his father before him, he has a natural ability for the work and is even beginning to think he might enjoy it. Then the creature asks for something he cannot give. The life of his sister. He has a window of just a few hours to save both their lives and so begins a bloody journey in search of rescue, revenge and redemption.