Perhaps the term ‘novel’ should be used cautiously, though. The Bath Fugues is composed of three intersecting narratives, each told in contrapuntal voices. As the title suggests, this polyphonic structure has a musical inspiration. The reader is alerted to this by an epigraph about Bach’s Goldberg Variations, the keyboard fantasia made famous by the pianist Glenn Gould and by the fictional psychopath Hannibal Lecter. But ‘fugue’ is an ambiguous word – it also describes a mental disorder, usually with symptoms of memory loss and identity confusion. The book’s main characters are well aware of this medical meaning; indeed, several of them teeter on the edge of madness. Often their flights of fancy take place in the tepid water of their own tubs – hence, bath fugues. (The last and sanest of the narrators prefers taking a shower, but even she occasionally relents.) Baths are not the only recurring motif here. The book could equally have been called The Bicycle Fugues, since the characters are just as likely to escape reality on two wheels.

The novel’s first narrator is a sixtyish Macanese Australian who goes by the name of Jason Redvers. Ex-jailbird, ex-art forger, painter manqué: Redvers has led a thoroughly shady life with more than its fair share of lucky escapes (not to mention a few suspicious deaths). After many years abroad he has returned to Sydney and started to write the unreliable memoir that makes up the first third of the novel. This proves to be a dense and mysterious text, ‘a choppy musical dedicated to counterpoint, without the axes of time and place, collapsing in upon itself’ – in short, a postmodernist fiction. One of its chief influences is said to be Montaigne, the patron saint of self-analytical littérateurs everywhere. The result is a peppery ragoût. There are flashes of gaudy vocabulary (‘sumac’, ‘simoom’, ‘siliceous’ and so on); there are learned asides on the grands hommes of Western culture, ranging from Bach to Bacon to Baudelaire (and that’s just the B’s); there are poeticisms and puns (an agent of betrayal is summed up as ‘Time’s wingèd Iscariot’). All of this is very funny and perfectly in keeping with the sort of erudite vagabond that Redvers claims to be. Even murderers can have a fancy prose style.

Redvers’s sudden return to Australia has been precipitated by the death of his closest friend, a bibulous academic called Walter Gottlieb. Just as friendship was one of Montaigne’s pet subjects, Redvers’s memoir examines his long and tangled relationship with the unfortunate Gottlieb (so unfortunate, in fact, that he died in the bath after apparently mixing Viagra with his Prozac). For decades Gottlieb had taught humanities at Sydney University, where Redvers began as one of his students and ended up as one of his drinking buddies. The novel’s descriptions of donnish life are deliciously acerbic, especially Gottlieb’s Canute-like struggle to stem the tide of post-structuralist theory then sweeping the university. Recognising that this was a hopeless task, he convinces Redvers to travel instead of pursuing an academic career.

Needless to say, this is not the sort of novel where a character might enjoy a run-of-the-mill gap year. Redvers’s peregrinations include a stretch in an Italian prison for financing the Red Brigades (during which time he reads Gramsci, of course) and then a long stint of la vie bohèmienne. Wandering through the Midi, he meets and marries the poetically named Marie de Nerval, an artsy aristocrat. This does not prove to be a blessed union, chiefly because Redvers cannot restrain himself from seducing his wife’s sister. The unhappy couple decide to move to Australia, where they drop each other faster than a hedge fund dumping sub-prime assets. Marie eventually marries Gottlieb (she is said to fancy intellectuals) and then persuades Redvers to take up lodgings in their Double Bay mansion. It is not long before disaster strikes. The Gottliebs adopt twin daughters, but one of them drowns in the mansion’s swimming pool. This seems to have been partly Redvers’s fault he was supposed to be watching the girls while their parents were off having sex, but instead he was enjoying a gin-soaked fugue on the banana lounge. Not surprisingly, there is plenty of guilt to go around.

As all this suggests, Redvers certainly has his work cut out for him in attempting to make sense of such a convoluted life. Many of his memoir’s loose ends are not tied up until much later. The book’s second narrative tells the story of his grandfather, a Portuguese poet called Camilo Conceição who had emigrated to Macau during the lastyears of the nineteenth century. Conceição’s experience in this exotic place is pieced together from several sources: the poet’s own lyrical confessions, various letters salvaged from junk shops and a rambling chronicle written by Walter Gottlieb. Indeed, it seems that Gottlieb is orchestrating the whole narrative for reasons of his own. Conceição was an opium addict, an obsessive collector and a keeper of concubines (readers familiar with Castro’s other novels will recognise some continuities here).

For Gottlieb, compiling the biography of this dissolute figure is his own shot at literary immortality, though this ambitious memorial act ultimately raises more questions than it answers. The book’s third and final section is another hall of mirrors. It consists largely of the journal of Dr Judith Sarraute, a medical practitioner living in northern Queensland (and one of several characters who share the name of a celebrated author). In the past, Sarraute had treated both Redvers and Gottlieb, learning intimate details of their affairs; she also has a close and slightly creepy relationship with Blixen, the surviving daughter of the ill-fated Gottlieb marriage. Though the doctor’s journal does shed further light on things, much remains unresolved. ‘All stories are caught in the forks of others,’ she comments unhelpfully at one point.

Nothing is easy in Castro’s fiction. Like its predecessors, The Bath Fugues is a cabinet of curiosities, filled with arcane knowledge and studded with gnomic epigrams (‘Envy is the sad embalming of lack and desire’). Its characters seem implausible, but fiction, of course, makes no claim to be real. On another level, it works as a serious meditation on the nature of writing. The poet Conceição, for instance, admits to ‘a deep hatred of novels’, while even the logorrhoeic Redvers claims to loathe his own literary output. The paradox, though, is that these compulsive scribblers produce writing of the highest order. Against their own stated expectations, they manage to capture the fugitive feelings and modest phenomena of daily life. There are, for example, lovely descriptions of landscape in Redvers’s memoir, and delicate evocations of thwarted love in Conceição’s pseudo-biography. Despite these gusts of lyricism, the “novel’s overall effect can be somewhat dispiriting. The various narrators describe a world that is almost always cruel and ugly. But this bleak outlook is also part of art’s domain, as much as any gentler vision of aurochs and angels.