As in many dystopian novels, the narrative hints at its back story through the ominous appearance in the text of unexplained proper nouns — the Change, the Breeders, the Others — before revealing that an environmental cataclysm has produced rising sea levels and extreme weather across the globe. Britain, which has been spared the worst, uses the Wall — a literal Brexit — to keep out both water and unwanted immigrants. As Kavanagh makes modest plans for his future, falls in love and finds small forms of consolation, there are shades of Kazuo Ishiguro’s “Never Let Me Go,” but trouble lies ahead, and the second half turns into an ordeal that evokes Cormac McCarthy’s “The Road.”
Like most of its literary precursors, “The Wall” opens long after the Change, which allows Lanchester to present his society as a given, without having to worry about the details of the transition — a luxury granted to novelists, if not politicians. The catastrophe evidently happened over a short period of time, creating a historical dividing line as decisive as the Wall itself, and everyone knows whose fault it was: “The world hadn’t always been like this and … the people responsible for it ending up like this were our parents — them and their generation.”
This kind of moral clarity has little to do with the real devastation wrought by climate change, which promises to be just gradual enough to allow those who caused it to avoid blame during their lifetimes. Lanchester’s vision of an agonized cultural reckoning seems like its own sort of wishful thinking, and even if we grant his premise, many of his conclusions — like the notion that most people would stop having babies out of sheer guilt — are less than persuasive. Yet if the novel succeeds only intermittently as a parable, it’s gripping as a story, especially when it leaves the Wall. As Lanchester puts distance between himself and his gigantic symbol, the plot grows less constrained, and the last hundred pages are full of tense action and sudden reversals that are mercifully unburdened by any allegorical significance.
The result marks a step forward for Lanchester, a formidably intelligent author who has sometimes stumbled over his undeniable gifts. His debut, “The Debt to Pleasure,” was so pleased by its Nabokovian conceit — a murderer’s confession posing as a cookbook — that it settled for a series of variations on the same dark joke. More recently, “Capital” was a credible effort at a big social novel that was so densely reported that its characters barely had room to interact or change.
For a certain type of realistic novelist, a shift to speculative fiction — which allows the writer to invent as well as observe — can be liberating. “The Wall” revels in this opportunity, but it occasionally falters under Lanchester’s decision, which echoes “Never Let Me Go,” to keep most of his people slightly colorless, as if to contrast their ordinary inner lives with their horrific situations. In practice, the narrator’s restricted voice prevents us from seeing his world as clearly as we should, and we learn frustratingly little about its most vulnerable actors — the climate refugees on the far side of the Wall.
The novel gathers momentum as it goes, and few readers will stop until they reach its final page. Early in the book, Lanchester toys with the idea of “concrete poetry,” in which a poem is typeset to look like its subject, like a house or a Christmas tree. In its closing lines, like the album of the same name, the novel doubles back on itself to take the shape of the Wall — but it lives most vividly in the places where its meticulous structure breaks down. Lanchester constructs a more elegant wall in prose than any politician could in concrete, but the limits that it imposes on itself are still barriers, no matter how artistically designed.