The Steep Approach to Garbadale, by Iain Banks

A change, they used to say, is as good as a rest, and anybody who managed to write 19 novels in 18 years was probably entitled to take a wee break for a wee dram. Between 1984 and 2002, Iain Banks produced ten novels, at least half of which were superb and a couple more very good indeed. His science-fiction alter ego, Iain M Banks, wrote another nine. This constitutes a pretty fearsome work-rate, and it was probably not surprising that the most recent efforts of both Bankses - the literary guy's Dead Air and the SF bloke's The Algebraist - showed distinct signs of strain. Thus it was that Banks ended up writing Raw Spirit, a non-fiction work concerning whisky, and then taking a year or two off.

Now he returns to the fictional fray, and it would be a pleasure matched only by a brimming tumbler of an 18-year-old single malt to be able to hail The Steep Approach To Garbadale as a spectacular return to top form for this most engaging and exuberant of literary entertainers. Unfortunately, it seems less the work of a giant refreshed than that of a virtuoso dancer or gymnast remastering his skills after an accident or injury. There are, inevitably, moments of characteristic brilliance and wit, but they are counterweighted by as many where the maestro's touch seems uncertain and "off".

The bravura opening, where a Mercedes-driving yuppie ventures onto an estate-from-hell in Perth, is an archetypal sleight-of-hand in which we are misled both about the literary genre we are inhabiting - a "Scottish novel" in the tradition of Irvine Welsh or Christopher Brookmyre? - and the identity of our protagonist.

The yuppie is Fielding Wopuld, scion of a wealthy family whose fortune is founded on the creation in Victorian times by his great-great-grandfather of a Risk!-style board game, called Empire! Now a US megacorp has turned it into a major chunk of their computer-game portfolio, and seeks to buy the family out. Rounding up opposition to the deal, Fielding has come to recruit the family drop-out, Alban McGill, to his posse.

It is Alban, not Fielding, who is actually the novel's protagonist, and his mission is to come to terms with his family heritage. This not only means resolving his relationship with his first cousin and teenage love, Sophie, with whom he enjoyed a brief and delirious affair before they were separated by the family, but also uncovering the truth about the mysterious death of his mother. The trouble is that, for all the time we spend in Alban's head, he rarely comes fully to life. Even for a reader whose political views are not a scintilla removed from Banks's own, it is somewhat disconcerting to see the author's hand so obviously up the character's back. You can practically see a Woody Allen-style "author's message" caption flashing at the bottom of the screen.

The Wopulds seem inspired by Orwell's dictum that Britain resembles "a family with the wrong members in charge." "Heavy-handed" is a term rarely applicable to Banks's work, but here the subtext has become the text.

Nevertheless - dinnae sweat it, big man. Better will come, and a master off his game is still a master. Banks's evocation of the tortures and travails of first love is moving and lyrical; his account of Fielding's attempt to use a laptop PowerPoint presentation to convince a pair of dotty old great-aunts is effective farce, and his description of a woman preparing her suicide is utterly scarifying.

One of the minions of the evil megacorp is a religious nutter who, splendidly, hisses, "Mister, you'd better pray there is no God!" before telling his colleague that Alban "believes we're descended from monkeys". When he's match-fit, Banks makes it all seem so effortless. So it comes as a shock when we see too much of the scaffolding.

Charles Shaar Murray's 'Crosstown Traffic' is published by Faber & Faber