The post-apocalyptic family film — sounds like some sort of sick joke, doesn’t it? (It’s one thing to kill Bambi’s mother, but quite another to make Earth utterly uninhabitable.) And yet after Pixar’s recent triumph WALL-E and the new fantasy-novel adaptation City of Ember, this seems to be an emerging Hollywood genre.

The titular city is quite a sight indeed: Set in a colossal subterranean cavity, Ember is lit from above by giant flickering lamps and populated with quaint, dilapidated little houses. A prologue explains that the city was established after the “end of the world” (no one bothers to explain why or how this happened) by a few hundred survivors, and the plan was to live there for 200 years and then return to the surface. But by the time Ember has begun to fall apart, the plans are lost, and the city’s loveable, clueless inhabitants are on the brink of apocalypse round two.

Destined to save the day are youngsters Doon Harrow (Harry Treadaway) and Lina Mayfleet (Saoirse Ronan, who delivers the film’s most engaging performance). With a mysterious box left behind by Lina’s grandmother, Doon’s penchant for finding and interpreting clues and an astonishing amount of luck, the pair goes toe-to-toe with Ember’s ne’er-do-well mayor (oddly underplayed by Bill Murray) and his sinister lackey Barton Snode (Toby Jones). If you’ve ever seen a kid’s movie before, you should be able to fill in the rest.

In fact, the general predictability of City of Ember is not its biggest problem. From a narrative standpoint, the film fails because it has too many “aha!” moments. Literally every 10 minutes, either Doon or Lina is discovering a major secret of Ember’s past; eventually, we stop caring. Rather than build suspense gradually, the film opts to intermittently expend any accumulated excitement on cheap revelations. This story would function better as a video game.

However, Ember does have its good areas. Caroline Thompson, the screenwriter, seems to have a unique gift for imagining thoroughly realized, endlessly interesting fantasy worlds on the page — she did it with Tim Burton’s The Nightmare Before Christmas and Corpse Bride, and she does it again here. The production design is fittingly breathtaking: From the first shot of the city, Ember is a living, breathing environment, complete with rusty trinkets, cozy rooms crowded with furniture and eccentric, engaging characters milling about from dawn to dusk. Aided by Xavier Pérez Grobet’s rich photography, the city strikes a perfect balance between the charming and the menacing.

Meanwhile, Gil Kenan (director of the well-received Monster House) has assembled a standout cast. Besides Ronan, Treadaway, Murray and Jones, we have Tim Robbins as Doon’s inventor father, Martin Landau as the senile mechanic Sul and Marianne Jean-Baptiste as Clary, Lina’s mother figure and the film’s token magical and wise guide. All in all, this second-rate family flick counts five Oscar nominees among its cast (including Ronan, who was nominated at age 13 for Atonement).

And unfortunately, City of Ember really is second-rate. It may boast a stellar cast, but I spent a large part of the movie simply wondering what such high-caliber actors were doing here. So many of the lines written for these stock characters have been spoken so many times before in kiddie adventure movies gone by; the film’s story isn’t dynamic enough to warrant taking itself as seriously as it does.

This isn’t to say that the movie isn’t timely — after all, the current financial and geopolitical state of affairs makes the apocalypse film frighteningly apropos. (I Am Legend, anyone?) City of Ember simply has nothing new to say, and tries to compensate for this lack of energy with a tedious plot and a large helping of visual panache. While the kids might be satisfied with the grand visual effects, the movie lacks the universal appeal of its family-film superiors — it mistakes style for substance. It isn’t the end of the world or anything, but it might feel like it.