DURING the ’50s and ’60s, the spectre of nuclear war loomed large.

Nations were crippled with fear and paranoia, constructing nuclear fallout shelters to sustain the population for months, if not years after an attack.

Jeanne DuPrau expanded the idea of subterranean refuges in her first novel, The City Of Ember, which was eventually published in 2003.

In this first book of an ongoing series, she imagined an entire underground community powered by a massive generator, cocooned from the apocalyptic horrors which befall mankind on the surface.

The human race endures while the planet heals, and in time, survivors hopefully find their way back to the surface.

The gargantuan, three-storey high sets, created in a hangar on Belfast docks, are spectacular - shabby, rundown and bathed in light from hundreds of bulbs which mimic the sun, Ember convinces as a self-sufficient community on the brink of collapse.

For the past 200 years, the bustling metropolis has survived under the power of a generator, but food stores are dwindling and machinery is about to fail, threatening to plunge the sanctuary into eternal darkness.

Graduate student Doon Harrow vows : “I will not sit around while Ember collapses. I’m getting into that generator, whatever it takes.”

City Of Ember feels a tad sluggish even at 94 minutes, with just two action set pieces (a close encounter with a giant tentacle-nosed rat at the midway point and a high speed, log flume finale) to quicken the pulse.

Digital effects are used sparingly, but are noticeable by their clumsiness against such impressive production design.

Saoirse Ronan and Harry Treadaway are both endearing as adventurous urchins but there’s not enough detail about their characters before the grand adventure begins (not in earnest).

Bill Murray plays his corrupt official so low key, he’s almost lifeless.

Martin Landau,Tim Robbins, Mackenzie Crook and Marianne Jean-Baptiste are all much better than their meagre supporting roles merit.