The fact that this is yet another dark, post-apocalyptical film for children should not keep you away from City of Ember. Adroit casting, interesting set design, a rousing story and a quick run time that doesn’t gratuitously stretch much over an hour and a half make for some rousing family entertainment. Based on the children’s novel of the same name by Jeanne Duprau, we find Saoirse Ronan, the young actor who was nominated for an Academy Award last year for Atonement, playing Lina Mayfleet, who lives, along with the rest of earth’s remaining population, underground in a threadbare city called Ember.

The Builders, who were trying to save mankind from extinction, placed them there 200 years ago, along with a giant generator to power the city and a magical box that would free them from their subterranean confines and lead them to the earth’s surface when it would likely be safe to live there again, in 200 years. Alas, the box has been misplaced, the generator is about to go, and the city is run by a corrupt mayor played by Bill Murray.

Lina, her young friend Doon (Harry Treadaway) and his crazy inventor father (Tim Robbins) seem to be the best hope for getting out of Ember before it crumbles to dust, even tough it’s believed that outside of the city there is “only darkness.” Look for fun supporting performances by Mary Kay Place and Martin Landau. Oddly enough this film appears to have fallen through the media cracks, which is surprising because it’s produced by Tom Hanks’ Playtone Productions, along with Fox Walden. The Fox tie-in is where it gets confusing: it is completely independent of 20th Century Fox and Fox Searchlight. Walden Media is committed to film versions of children’s classics, such as Charlotte’s Web, The Chronicles of Narnia, Nim’s Island, and more, and has apparently been involved with so many different studios at one time or another it’s hard to keep the genealogy straight. But just because a massive advertising campaign has not been mounted for City of Ember doesn’t mean that it’s not a worthwhile film. Aside from some awkwardly rendered special effects, it’s good, clean fun for the whole family.

Rated PG.

-- Lisa Johnson Mandell