If City of Ember brings to mind Plato’s allegory of the cave, consider yourself broadly educated. The Greek philosopher used a parable to make a point. He imagined a group of people living in a cave like bin-Laden, the fire casting their shadows on the wall. The folks believed that their images were reality and that the cave was the whole world. Some curious ones tried to climb out but, blinded by the sun, they returned. The few who made it out were amazed at what they saw and returned only to tell others what they witnessed. They saw the truth (the sun) and became society’s philosophers. When they told their story to the “just folks,” they were laughed at as elitists are in our own time.

The City of Ember—“ember” meaning a smoldering hunk of wood or coal—is like Plato’s cave in that the 300 or so people living there seem unaware that there is a great, big outdoors well beyond their imaginations. The artificial city, which looks like a giant interior mall such as you’ll find in Toronto or Minneapolis, houses residents who have known no other existence. It’s always nighttime, however artificially illuminated, such as that experienced six months of every year by research scientists in Antarctica. The city was built to last for 200 years in order to protect the people from an unexplained disaster, probably some cataclysm almost as bad as today’s financial meltdown. The two centuries are now up. Though the folks seemed happy enough, food shortages threaten, the generator which supplies electricity is fizzling out, and the box holding instructions for egress from the city is nowhere to be found. Enter two 12-year-old heroes, Doon Harrow (Harry Treadaway) and Lina Mayfleet (Saoirse Ronan, last seen in Atonement). If they can find the magic box which had been entrusted to the first mayor and decode the now-deteriorating paper instructions to leave Ember, they will save civilization.

They say that if the first thing you compliment is the set (or the music or costumes), the movie is in trouble, and indeed City of Ember, admittedly targeted to grades 4-7, benefits from Martin Laing’s production design. The movie, which could easily have a home on the stage since all the action takes place within the set, features all sorts of gadgetry that might have been used in a British documentary paying homage to the Industrial Revolution. Ember lacks all the gizmos that are vital to life today—iPods, X-boxes and CD burners are nowhere to be found.

The kind of action that would enthrall the young ones takes quite a bit of time to get underway. Instead, director Gil Kenan, employing Caroline Thompson’s adaptation of Jeanne Duprau’s children’s book, lazily looks in on the goings-on within the city. The boys and girls graduate from school and receive work assignments from the mayor (Bill Murray, made up with a pot belly and a medallion hanging from his neck), who directs each graduate toward a specific field like messenger, pipe worker or generator assistant. For humor, the story calls on Sul (Martin Landau), an aged generator tender, to fall asleep at crucial times. Verbal wit is noticeably absent. A creature that looks like a cross between an octopus and a giant spider threatens to eat the story’s heroes, though we wonder how this grotesque people-eater got into the city, since the residents have lived for 200 years creature-free. The only real exciting action of the film occurs as the kids must traverse a near-tidal wave that envelops the area and get their bathtub-size boat through a wooden water wheel without getting permanently stuck.

There were no children at the critics’ screening to give viewers some insight on how the movie will go over with its target audience, but those who liked Gil Kenan’s last movie, Monster House (two adolescent boys and a girl sense that the house across the street is alive and swallowing up people), might get a charge out of this City. While Monster House had Steven Spielberg as an executive producer, this one lists Tom Hanks among the sponsoring execs. Maybe Hanks knows something that might puzzle other adults, but City of Ember comes across as a glum effort with actors who seem not to be having a good time. And this was filmed before the stock market crash.