Joyce’s influence is writ large here, and The River Capture could be read as an extended love letter to the great novel of interiority. Luke shares Leopold Bloom’s affinity with animals, scientific observation and fluidity of gender and sexuality, even thinking of Bloom as a “second self”. The move from the third-person to the first in the final chapter echoes Molly Bloom’s soliloquy. The most extended homage is the penultimate chapter, structured in terms of questions and answers like the catechism of “Ithaca”, the penultimate chapter of Ulysses... Luke once had dreams of writing a book about Joyce but has long since abandoned the hope that he might “catch the peculiar cast of Joyce’s mind . . . convey what he felt for Bloom”. In a lovely wink to Costello’s own project, Luke thinks: “If he were a novelist he might have been up to the task.” Costello certainly is.

From the beautifully modulated opening sentence of Mary Costello’s second novel, we know we are in Ulysses territory (first line: “Stately, plump Buck Mulligan came from the stairhead, bearing a bowl of lather on which a mirror and a razor lay crossed”)... To take on the ne plus ultra of literary modernism and bend it to one’s own ends is an audacious act of literary ventriloquism and one that Costello pulls off astonishingly successfully. She renders Luke as a convincing blend of Leopold Bloom and a modern-day man with his own particularities. Likewise, the relationship between Luke and the tidal river, and the patterning that underlies the novel’s structure, are accomplished and satisfying; but having divided the book so strictly into two, the incoming tide that powered the first half becomes rather obstructed, and is at risk of petering out. Nevertheless, Joyce devotees will discover much to enjoy in this clever homage, while fans of contemporary Irish literature will find a subtle, slightly melancholy, engrossing read.

There are scenes too of unusual economy — two pages delivering the death of Luke’s mother, one page on the sufferings of a childhood friend, which gives us, briefly, a side of Luke we haven’t seen — which merit rereading on their own. And Costello allows us into Luke’s thoughts without putting an authorial thumb on the scales, so the reader comes to understand each character through their scattered thoughts only; this gives the narrative a rare authenticity.

Mary Costello’s audacious second novel, the successor to the Costa-shortlisted Academy Street, confirms her as one to watch... ‘River capture’ is a geological phenomenon whereby one river diverts the passage of another. But central character Luke O’Brien — a bisexual, possibly bipolar Irish farmer whose land incorporates just such a channel — spots in it a loaded metaphor for the way in which a devastating revelation knocks his own life off course. Turning away — intentionally though a little disappointingly — from the storyline she has set up, Costello thereupon diverts her own novel, and its dramatic denouement also becomes a homage to Ulysses, with which former teacher Luke is obsessed. It’s a gamble that doesn’t really come off, and several strands feel cut short. But Costello’s characters — who might easily have seemed too writerly — have a persuasive, urgent life that leaves a lasting impression.

Mary Costello’s first novel, Academy Street, was a bestseller and won a host of prizes. Set in the US in the 1940s, it recalled Colm Tóibín’s Brooklyn in its quiet, tightly written intensity, a novel like salt on the tongue. Her follow-up, The River Capture, is a more peculiar thing. As elegantly written as her previous book, it is more obscure in its intentions, more adventurous in its ambitions... This geological metaphor also seems to nod to the radical stylistic change that takes place two-thirds of the way through the book, when it moves into a kind of dispute with the self, all of it in language that is increasingly Joycean. Questions are posed and answered, there are long passages of exquisite and impressionistic prose, Luke’s mind appears to have been unblocked, and all comes rushing forth.