Corporate-minded land surveyor Nicole is sent to investigate an agricultural issue on Romney Marsh. Sent as a reluctant replacement for her predecessor, Martha, who went missing some months before, Nicole quickly finds herself unable to work and essentially stranded in an unwelcoming landscape she cannot tolerate. She is visited repeatedly by the mysterious Heather, who drags Nicole on tours of the area, debating and regaling the outsider with local stories and wisdom. Gradually Nicole becomes aware of encroaching, strange phenomena, from finding Martha’s camera buried in the beach, to the feeling she is being observed. Then, one night, these experiences reach fever pitch and the truth of the marshland is unearthed.