Weathercock by Glen Duncan

The merry hell of devout young Dominic

With Christian names taken from the two main monastic orders and a surname suggesting both a monk's cowl and a criminal disguise, Dominic Francis Hood is well named.

Unusually for a child of the Sixties, his imagination is steeped not in teatime TV and American comics but the Devil-obsessed doctrine of traditional Roman Catholicism. Dominic is born into a devout family: his father refers to the Turin shroud as "a photograph of Jesus". The defining moment of his childhood comes when, aged eight or 10 (depending on whether you trust the dates at the beginning or end of the novel), he seemingly kills a fellow pupil. Father Ignatius Malone, a visiting priest and exorcist, restores the victim to life.

Malone, who exerts an intense influence on Dominic across decades and continents, views life in purely Manichean terms (until his own dramatic apostasy). For him, the world is a battleground between God and the Devil, and the choice for humanity is clear. Dominic, while acknowledging both Malone's argument and power, allies himself with the Devil (according to his own definition) when he engages in sadistic sex acts, first with fellow pupils and later - more damagingly - with Deborah Black, the adopted daughter of the matron of an old people's home, and her subnormal sister, Alice.

Black (another symbolic name) plays the bad angel to Malone's good one. She encourages Dominic to explore his sickest fantasies, arriving in his life at critical moments, first to destroy his chance of conventional happiness by forcing him to horrify and humiliate his fiancée, Natalie, and second (in a scene overly reminiscent of Pulp Fiction) almost involving him in a sexual murder. Dominic's shifting between Malone and Black, and what they represent, gives the novel its title.

To borrow from the ecclesiastic imagery in which it is steeped, Weathercock is a curate's egg. It is by turn ambitious and audacious, and clumsy and lurid. To new readers it offers the perfect introduction to Glen Duncan's world, being both a compendium of his favourite themes and a summation of his three earlier novels. It combines the prurient, pornographically inclined hero of Hope, the sexual violence of Love Remains (by far Duncan's finest book) and the jokey diabolic presence in I, Lucifer.

The best writing is to be found in the portrait of Dominic's intense intimacy with two fellow adolescent misfits, Kelp and Penguin. Their casual insults, metaphysical speculation and sexual rivalry all come across as horribly true. It is a problem, however, that Kelp's clairvoyance, bizarre death and ghostly manifestation are never integrated into Dominic's story in any way beyond the chronological.

The worst writing is to be found in an exorcism that Malone conducts on a young boy in Goa, which Dominic either providentially or over-conveniently (depending on your point of view) happens to witness. It would take a Dostoevsky to do justice to the horror and mystery of the ceremony. Duncan's description, in which "an enormous coiling black turd is tubed out" of the boy's mouth, falls risibly short.