Smug old swinger CJ "Pops" McCool has been strutting his stuff in Mood Indigo, rural Cullymore's top nightspot, since the 1960s, when he was "unashamedly the dapper dandy in my crushed-blue-velvet pants and frilly pink nylon shirt". He still enjoys a turn on stage with Vesna, his svelte and seemingly attentive not-quite-wife from Croatia.
Back in his heyday, his suavity had quickly snagged the attention of Dolly McCausland, Cullymore's own transgressive beauty who would dance on the club's tables and flirt with "Mr Wonderful" McCool. However, his youthful summer of love turned distinctly wintry after McCool peered through a Butlins chalet window to see Dolly seductively undressing his pious rival, a theology student who was also Cullymore's sole black resident.
Forty years on, the village has evolved into a Dublin satellite suburb, but McCool, a self-styled "hep cat", has stagnated in the calamitous events of his youth. Filtered into his rosy account of schmoozing are more alarming recollections of his bastard childhood. His father is nominally Dr Henry Thornton, a Protestant so frosty that it's left to a local "Catholic cock" to service desperate Lady Thornton – McCool's hapless mother – in their barn. Banished from the manor and brought up by a daffy tenant on the edge of the estate, McCool eventually finds success as a farmer while tussling with emotional instability and fecund paranoia.
While confined in a psychiatric unit, McCool hallucinates his cosseted step-brother emerging from the brick-sized ventilation grille. He congratulates himself on not being fazed by the sight of a nine-inch Lulu or Herb Alpert – but a tray of eggs beseeching him in a farmers' market sets him off.
For all McCabe's narrative skill at eking McCool's more unhinged episodes out of the smooth narration of his past, The Holy City is not without problems. Quite what the holy city is, for example, is never made clear. At times the phrase refers to a 19th-century anthem, but is also used to suggest the haven of maternal love, sexual congress, faithful love or an ecstatic vision of the new Jerusalem. While this mutable image partly reinforces McCool's erratic grasp of his own personality, it also congests the narrative without obvious benefit – as do McCool's identity anxieties over his "spiritually infirm" rational Protestant and hysterical Catholic genetic make-up.
Previous McCabe novels have worked well by deploying stock-in-trade small-town, disturbed, unreliable characters who engage the reader with an undeniable charm. The Holy City is hampered by McCool's peculiar unreliability, a needy emotional excitability which lies somewhere between the narrators of Nabokov's magnificent Pale Fire (brilliantly, obsessively mad) and John Lanchester's The Debt to Pleasure (urbanely murderous). Both these novels enjoy a precision of viewpoint that feels absent from the ebb and flow of McCool's fantasies and paranoia.
"Unsustainable levels of emotion, pure and simple," McCool claims to be the root of his problems; but The Holy City struggles more with a vagueness of affliction. Despite a concluding dash of gothic, its protagonist's idiosyncrasies don't give sufficient momentum to the reader to piece together his fragmentary unburdening.