Rick Deckard is holed up in the woods with android lover, Rachel. She's on ice, thawed out briefly every so often to provide a little R&R for a retired Blade Runner; a slow-motion death. But the past has a way of catching up, here in the shape of the Tyrell Corporation: they want him back, to chase down that fabled sixth skin job left over at the end of the movie. And they are not asking nicely.

So back to the mean streets of post-millennial Los Angeles Deckard goes, revisiting his past in the various battered shapes of characters from the film - Sebastian, Pris, Holden, even Roy Batty - hunting down the truth about the nature of his reality.

Possibly. Much of this is calculated to the point of irritation. Example: the rain-lashed city of before is now in its dry season, the streets clogged with parched red dust. It's a contrast, do you see, an original idea, spelled out as surely as one of those huge neon signs that so dominate the cityscape.

Which would be okay if Jeter's book wasn't quite so structurally unsatisfying. The occasional half-hearted action scene is shadowed by page upon page of extraordinarily didactic dialogue. The plot doesn't so much happen as get relentlessly explained. Characters are told again and again that they're not real, while the reader surrenders to fatigue. You get a measure of truth in the end but gave up caring somewhere about page 200 of this exceptionally long novel. Characters - even Deckard - are barely recognisable. No personality, no life, they exist merely to expedite Jeter's banal, repetitious plotting.

Worse still, however, is how ill-served the perfectly formed Blade Runner universe is by this insipid and largely redundant sequel. There is a completeness to the (second) movie, a resolution that, while inferior to Dick's brilliant novel, is intellectually and emotionally satisfying. In searching for a reason to do this, Jeter rips apart that elegant despair for a simple story hook. The methods and meaning of Scott's film are jettisoned in favour of a confused and confusing scrummage of conspiracy and double-dealing. We even get an etymology lesson in the derivation of blade runner itself (dialogue, of course) when we all know it was just great-sounding Burroughs. Jeter is a fine writer, but this is far from his best.

What it cries out for are Deckard's meditations on finding that unicorn outside his apartment, not tooled-up, racing around the city; more glum pessimism, less exploding airships and cod-SF moves. If the oft-threatened follow-up movie ever goes into production, we can only hope the script finds its inspiration elsewhere.