An abusive priest, damaged teenagers, the wilful ignorance of the church; a structure which incorporates flashbacks and flashforwards, giving the main narrative a disrupted, staccato quality; dollops of Edgar Allen Poe's outpouring of Gothic gloom, "The Raven" - by the standards of contemporary popular fiction, Retreat is a startlingly ambitious book.

It opens as the senior girls of St Martin's convent school in Dublin begin their Easter retreat, during which they have been advised to pray for vocations.

The main characters are introduced one by one, then their backgrounds are pencilled in through a series of flashbacks.

"Turn back the clock and meet Anna McBride as a little girl, pale-faced with dark red hair. . ." Each girl is labelled as neatly as if she bore a tattoo: Kitty O'Dowd, bad girl, Bernadette O'Higgins, whose mother is dead, Treasa O'Donoghue, "whose bottom stuck out so that the pleats of her tunic did not fall neatly over it", and Mary Oliver, who is blessed with an eating disorder, a mysterious (and missing) French father and a fondness for rolling nails around in the palms of her hands. Oh, and a vocation.

The scene is thus set for a jolly girls' boarding-school jape: and indeed, for much of the book, that's exactly what we get.

There are, of course, hints that something nasty is lurking in the school corridors - or, more specifically, in the confessional.

But when the full story of Father McMorrow and his unholy proclivities emerges into the light, the jolly hockey-sticks tone suddenly becomes lamentably inadequate; and for its final third, in a belated attempt to shift into top gear, the book adopts an unpleasantly coy, self-regarding smugness as the heroines plunge wholesale into the joys of unadulterated adulthood (mostly, of course, the joys of sex).

Retreat depends on a series of coincidences and conjunctions which, while perhaps intended to give it depth and seriousness, simply don't ring true.

The priest is also somebody's uncle - well, fair enough.

But Anna McBride and Mary Oliver's long-lost French father as a couple? Ho, hum. Andrew, Lansdowne Road lad and serial seducer? Give me a break. And what are the chances that the entire group of central characters would turn out to have been - OK, let's not give away the denouement, but if a novel is to explore subjects such as these in any depth, an author would need to seek out a more suitable role model than the Chalet School books.

Arminta Wallace is an Irish Times journalist