Fox Walden's film of Jeanne Duprau's children's book City of Ember stalls at the intersection of fantasy and science fiction.
While the storyline hearkens back to Alice in Wonderland and The Wizard of Oz, where young people navigate a weird other-world, the film is actually set in a dystopian underground that is the realm of sci-fi.
And that genre requires that any weird other-world must have a coherent logic and social structure. While director Gil Kenan and writer Caroline Thompson's film leans heavily toward children's fantasy, it leaves science-fiction holes.
The story begins at the end of the world, we are told. But what caused the end of the world is never mentioned. The remaining rulers of society – all middle-aged, English-speaking Westerners – send what is left of humanity to an underground city built to last two centuries, after which it will apparently be safe to come up for air.
A single box, set to open in 200 years, will explain everything, including how to escape from this City of Ember.
Where to begin with this silly tale? Are we supposed to believe that the old world above ground was erased from everyone's memory? No great-grandmothers' tales of life in the fresh air? Or that survivors have subsisted on mostly canned food for 200 years? Or that everyone blindly obeys a succession of mayors, the latest one played by Bill Murray as if he doesn't believe it either?
It falls to two high school grads, Doon (Harry Treadaway) and Lina (Saoirse Ronan), to question the underworld order. Doon realises the generator powering everything is falling to bits. A Mr Fix-It like his dad (Tim Robbins), he longs to get his hands on the machinery, but his job has been assigned to him by lottery.
Lina's ancestor, a previous mayor, died before he could pass on the crucial tell-all box. Now she discovers it and starts to plumb its secrets.
The city set, constructed in a ship-building hangar, resembles a corner of Dickensian London in permanent twilight. Communication devices don't exist, so messengers like Lina tear around the streets. People's clothes look like they belong to a community theatre production.
In truth, despite the enthusiasm of Andrew Lockington's insatiable score, there is little here to quicken the pulse. Treadaway and Oscar nominee Ronan (Atonement) bring plenty of verve to their parts, while their elders overact terribly.