Books: The Sopranos by Alan Warner, Cape pounds 9.99: Make mine a treb le

THERE ARE certain things you should have at the ready when you're reading Alan Warner's new book: a few doses of Alka Seltzer (in one scene, two 17-year-olds sink nine gins, one Sambuca, 18 tequilas, and two Bloody Marys); tissues, if you're the type to be affected by dying teenagers, botched miscarriages, dead puppies; and a fair dose of patience - although The Sopranos is mercifully nowhere near as rambling and esoteric as its predecessor, These Demented Lands.

Warner shot, as they say, to literary fame with his debut, Morvern Callar, the story of a supermarket worker who escapes the drudgery of her life by passing off her dead boyfriend's novel as her own. It was closely followed by the disappointing These Demented Lands. The Sopranos was written in about six months as a break from a novel about a railway worker that he's been working on for 10 years.

In it, Warner has been pulled back to his lodestone - the Port, the apparently fictional small Scottish coastal town where the inimitable Morvern began life. Five girls from the convent school are on their way to a choir convention in Edinburgh to sing songs "about cattle and death". None of them has the slightest intention of winning because they want to get back early to go clubbing. Edinburgh, however, proves to be an alien, urban landscape, and their separate odysseys across the city, through vast amounts of alcohol and assorted dodgy blokes, ensure that they return much altered to their inhibiting small town.

It is a tamer and more localised rites of passage novel than Morvern Callar, but there are still no concessions for shrinking violets in Warner's writing. As the bus weaves its way to the capital, bits of the girls' pasts are lobotomised before our eyes: Orla's leukaemia, Chell's traumatised parentage, Fionnula's sexual confusion, Manda's poverty in a house where "the walls are so thin ... that when she takes a bath ... the old man next door knows she's right there, in her bath and Manda can hear him wanking hisself off". His insight on female teenagers is, as ever, astonishing. Take the description of the girls getting dressed in a McDonald's toilet: Chell, he informs us, is wearing a "V-neck leopard-print short-sleeved top [and] creamed coloured skirt cut on the bias with brown decorative buttons on the front of waistband. Short." Does he have a hotline to Miss Selfridge or just a very understanding wife?

But the lapses in tone and focus which blighted his second book creep in here at times. The narrative concerning the priest and frustrated novelist Father Ardlui seems pointless and disruptive. The passages in the school, prior to departure on the bus, with censorious nuns and an errant parrot who interrupts the Hail Marys with streams of Spanish swearing, bring to mind the girls of St Trinian's. Warner is still indulging his irksome habit of self-referentiality in odd, supposedly intriguing signs. "Take in A/W" the Sopranos scrawl on toilet floors, road signs and windows. Whose intials are those, I wonder?

Warner doesn't need to pull these postmodern stunts: they just serve to undermine the realism and sympathy with which his best writing pulses - and much of the book is written with sensitivity and passion. If you can, forget the convent antics, unnecessarily split narrations and annoying games, get in the tequila slammers, prop youself up at the bar, and enjoy it.