Stripped to the bear essentials

THE TURNER PRIZE 2007 SHOW ***

TATE LIVERPOOL

MOVING the Turner Prize 200 miles north to act as a curtain-raiser for Liverpool's stint as European Capital of Culture 2008 has done nothing to dent the power of the prize's publicity machine. The press view was swarming with London art critics and camera crews getting under one another's spiky designer-clad feet.

Early reports are that visitor figures have not been dented either: demand to get to the fourth floor of Tate Liverpool in the opening week was so high the lift broke down. It's being compared with the opening of Primark in the city. Enough said.

The Turner Prize generates publicity like no other art prize, which has opened it to accusations of courting controversy, and rewarding sensation over substance. Which all makes this year's shortlist, ironically, a bit of a shock. Zarina Bhimji, Nathan Coley, Mike Nelson and Mark Wallinger are, in their different ways, earnest, engaged artists - so much so that some commentators have dismissed them as "dull". No tabloid feeding frenzy? Well, that's just no fun.

No-one seems to know exactly how the Turner Prize is judged. When it is presented on live television on 3 December, will it be on the basis of a year's (or a lifetime's) contribution to contemporary art, or about the work in this show?

This question is particularly relevant this year. If the judges are taking the long-term contribution route, Nelson, and especially Wallinger, have a head start. Both have been nominated before; Wallinger is currently the bookies' favourite. But neither are at their best here. If the approach is to judge the "work in show", the field is still wide open.

Regrettably, it is not an easy show to navigate. The normally airy space has been transformed into a labyrinth of dark corridors and boxy rooms. Having chosen four artists with more to say to one another in terms of ideas than most shortlists, they have arranged them like predators in a zoo, each with discrete territory.

Granted, some of the artists have placed very specific requirements on the space: Mike Nelson has created a mini version of one of his labyrinthine walk-through works in three rooms and Amnesiac Shrine returns to a strand of practice he developed in the mid 1990s, based on ideas "sent" to him by an imaginary biker gang of Gulf War veterans.

The bikers act as a conduit to a realm of fantasy. Passing the charred remains of a campfire, you enter the central room, which is divided into a grid of four smaller rooms with narrow corridors between them. Peering through holes punched in the wall, we discover an eerie desert landscape punctuated by pockets of light and surrounded by mirrors which make it appear infinite.

The trouble is that it offers little more than the momentary frisson of looking into a fantasy realm. The work seems to resist attempts to imbue it with greater meaning. And unless you've been following Nelson's work closely for the last 20 years, you will feel as if you've been parachuted into a foreign country with no roadsigns.

Nathan Coley is also staking out his territory physically with "threshold" sculptures (a spar of oak over which you either step or trip) at entrance and exit. While this made some sense in his show at doggerfisher in the midst of the Edinburgh Art Festival, here it feels like a bit of petty territorial marking.

However, Coley has one work that really stands out: his text work, There are no Miracles here, spelled out in lightbulbs fairground-style, which was the highlight of his show last summer at Mount Stuart. People go to galleries - as they go to the countryside - in search a bit of enlightenment or transcendence in this secular age, and this work is just as pertinent here.

Coley is a rationalist and if his work has a weakness is that it can be rational to the point of coldness. What is wonderful about this work is the way in which it undermines its own best intentions. But introducing the possibility of "miracles", things which cannot be legislated against, it seems to hint that transcendence is possible after all.

His new work made for this show is the scale model of a "typical English terraced house", the words "Hope" and "Glory" inscribed on its sides. It speaks of a country reluctant to let go its colonial past, a nation of homeowners obsessed with having their own four walls. But as a Scot, Coley has an outsider's take on the Land of Hope and Glory, just as he does on "typical English" homes. At the heart of this anglocentric art prize, he has made what might just be the most subversive work in the show.

If Coley's work tends to cold clarity, Zarina Bhimji's photographs and film do the opposite. They are redolent with sensation, light, texture, and with using these as a metaphor for other things - loss, hope, displacement, exile and so on.

Born in Uganda, from where her family were exiled under Idi Amin, she works chiefly in East Africa, Zanzibar and India photographing spaces, usually without people, but full of resonances of absence: layers of graffiti on an old wall; a chipped mother-of-pearl mosaic on a former palace; a row of machine guns primed and ready for use by some nameless guerrilla army. Essentially they are documentary photographs - good ones, at that - and withholding information about the context in which they were taken doesn't make them otherwise.

Her film Waiting was made in East Africa in a sisal factory. Filmed after hours, the machinery lies silent, strewn with wisps of the hair-like fibre. It's beautifully lit and luxuriates in detail, using film the way some artists use paint. It's beautiful as far as it goes, and she does at least recognise that there's a limit to the amount of time people are prepared to watch nothing happening.

Mark Wallinger is a very clever artist, so one suspects he knows this too, yet he has simply chosen to disregard it in his film Sleeper, his sole contribution to the show. It shows the artist in a bear costume lumbering around the hallways of the Neue Nationalgalerie in Berlin at night; he runs, hides, waves to passers by, lies down to sleep. And it's 150 minutes long.

The bear, we're told, is the heraldic symbol of Berlin. In the city once subject to some of the heaviest surveillance of the Cold War, he is a "sleeper", or double agent, a Brit disguised as a bear disguised as a German. Or something like that. And so on.

Nevertheless there is something heart-rending about this vulnerable figure, like an extra from a children's show, imprisoned in Mies Van Der Rohe's stark palace of glass, wood and concrete. It's whimsical and sad and a little bit daft, but it doesn't take us anywhere much beyond itself.

Wallinger was nominated for the Turner Prize because of State Britain, his 40m-long reconstruction of Brian Haw's one-man anti-war protest after it was evicted from Parliament Square. It was a vital, urgent work which engaged art lovers and non-art lovers alike. Few were in any doubt that it deserved to win the Turner Prize.

But State Britain is not here and by showing a work made in 2004 which lacks the same power to engage, Wallinger may have forfeited his chance of an easy win. That leaves the field open, with everything to play for, though it might be best not to expect any miracles.

• Until 13 January