Prior to Umbrella, his 2012 Booker-shortlisted novel, the main pleasure in reading Will Self's fiction was to wonder how long he could keep the madly spinning plates of his surreal conceits aloft before the whole narrative came crashing down.

A prodigiously imaginative writer, Self's combination of the feverishly grotesque with a rococo vocabulary ensured his books were always compulsive reading, even if they never felt as satisfying as the best of his essays and journalism. In Umbrella though, and now with its loose sequel Shark, Self has found his true discipline; no longer interested in exaggerated satire, he has become instead a kind of archaeologist, exposing the psychic and technological stratigraphy of the century, and of a culture that has been moulded by the twin forces of mass production and consumerism.

In Shark, recurring character Zack Busner is again the orchestrating presence, presiding here over Concept House, an exercise in communal living and non-invasive psychiatric care part-modelled on the theories of maverick Scottish psychiatrist RD Laing, who is elliptically mentioned as Busner's mentor. The most destabilising inmate of the House is The Creep, aka Claude Evenrude, who claims to have been the targeting officer on the Enola Gay as it delivered the Hiroshima bomb. Claude is in fact a survivor of the USS Indianapolis, the ship that transported the bomb in late July 1945 and was later sunk by a Japanese submarine in the Pacific. The horrific ordeal of the survivors, picked off by sharks as they waited three days to be rescued, is the source of Quint's backstory in Stephen Spielberg's 1975 film Jaws, a film that in one strand of the novel Busner watches with his youngest son.

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Moving parallel to the Concept House plot is the harlot's progress of Jeanie (later Genie) Gruber. Brutalised by her foul and overbearing mother, Genie dedicates herself to the counterculture of the early 1970s, falling into prostitution, drug addiction and, circuitously, the peace movement protesting at Greenham Common, the RAF airbase where the United States stored its first-strike nuclear arsenal. By the 1990s she is working in one of the veterans' homes established by Michael De'Ath, nephew of the Audrey De'Ath who was the central character in Umbrella, and brother to the pacifist alcoholic Kins, who (just to complicate matters) may be Genie's biological father.

Years after the Concept House debacle, Claude has become a patient at this hospital, where he calls himself Quint and spends his time redacting all incidents of the word "shark" in the original Peter Benchley novel of Jaws. As it transpires, Michael De'Ath was on the Enola Gay as the official RAF observer, and although his rectitude contrasts sharply with Claude's full-blown psychological collapse, both of them have been profoundly altered by the part they played in the Hiroshima bombing. When Busner's disreputable colleague Roger Gourevitch arranges an acid trip to break the increasingly unbearable tension in Concept House, these competing psychoses blend together in a space where time has become infinite, and where the memories of Claude's ordeal can finally be unlocked.

Images swirl and recur throughout the book, moving between different characters and zones as if scattered on the time stream by the transgressive force of that atomic explosion; from the symbol of ouroboros, the snake swallowing its own tail, to the numbers 8.15, which is the time Little Boy detonated over Hiroshima. Swimming smoothly beneath the surface of the narrative is the image of the shark, breaking the water as a minatory simile here and there, and standing as a wider symbol of the century's rapacious and destructive appetite.

A stream of consciousness presented as a single block of text, skipping between characters mid-sentence in a blur of italics and ellipses without chapter, page or paragraph breaks (as a nod to that summit of High Modernism, Finnegans Wake, Self even ensures that the final sentence of the book wraps around into the first), all this might sound reader-repellingly dense. It is testament to Self's skill and confidence as a writer that Shark does not feel overwhelming, but swiftly draws the reader in. Although occasionally too diffuse for a stand-alone novel, with Genie's plot not quite justifying the amount of space dedicated to it, as part of a wider project it is a major achievement. Focusing on his characters and themes with real depth and seriousness, drilling down to the intersection of military technology and modern psychosis, Self is now anatomising the 20th century with as much imaginative power as his great mentor, JG Ballard.