il Kenan's CG kid's film Monster House was half great, and so too is his follow-up City of Ember, a fantasy tale (based on Jeanne Duprau's novel) about a post-apocalyptic human society in a subterranean metropolis. Lit only by electric lamps and marked by crumbling brick, leaking pipes and all manner of ingeniously constructed devices (made up of cogs, pistons and wire), Ember is a superbly crafted environment, recalling not only the dreamlike nocturnal landscape of Jean-Pierre Jeunot's City of Lost Children but also the self-contained, sub-aquatic art-deco setting of last year's superlative videogame Bioshock. Kenan's production designers breathe vivid, animated life into this dank urban milieu, which is falling apart thanks to a central generator on its last legs. Yet it's Kenan's deftness at evoking a sense of fanciful adventure, amazement and childlike wonder—through sweeping, stirring cinematography synchronized to adolescent fears, anxieties and courage, and a score that hits all the right rousing notes—that gives heart to his story about two kids, Doon (Harry Treadaway) and Lina (Saoirse Ronan), who discover a box created by Ember's founding Builders that holds the secret to escaping their dying home. City of Ember is a film of maps and clues deciphered, of mysterious gadgets wielded, of codes broken, of villains evaded, and of long-concealed passageways navigated. Still, though Kenan's first live-action effort has a fleetness befitting a race-against-time odyssey, it also often feels unnaturally harried, with many sequences so rushed that one suspects studio runtime dictates as the culprit. This chopped-up quality unfortunately extends to other elements as well, from the random, without-explanation appearances of a mutant rat-like creature, to an evil mayor (Bill Murray) and Doon's dad (Tim Robbins), whose thinly devised personalities, motivations and backstories thwart the script's attempts to convey the vital bonds shared between generations. Nonetheless, a sumptuous atmosphere and two spirited lead performances from Treadway and Ronan ultimately trump (if just barely) such storytelling deficiencies, as does a finale that expresses, in Doon and Lina braving the darkness to seek the light, a spirituality that's understated and malleable.