Ravaged by the Change, an island nation in a time very like our own has built the Wall―an enormous concrete barrier around its entire coastline. Joseph Kavanagh, a new Defender, has one task: to protect his section of the Wall from the others, the desperate souls who are trapped amid the rising seas outside and are a constant threat. Failure will result in death or a fate perhaps worse: being put to sea and made another himself. The Wall is the dystopia that John Lanchester has created, an environmental fable that manages to be a calculated extrapolation of present anxieties about rising sea levels, anti-refugee populism, post-Brexit scarcity, and intergenerational conflict.