Three walls kept back the sea from the farming land adjacent the Lincolshire Wash. The first inner wall had been built under the supervision of Roman soldiers during their occupation of England. The second inner wall had been built in the 17th century to claim more land from the sea and help feed a growing population. The outer wall had been built by supervised convicts from the local jail in the 20th century. Simon Tailor, a leading light in the local nature conservacy group persuades the farmer to lease the land and breach the walls to form a new wetland habitat. As the sea regains its original domain it reawakens those past spirits from each era. Simon encounters the spirits and draws others into his quest for confirmed sanity. Until a perhaps inevitable, dreadful end.