City of Ember

City of Ember is a 2008 science fiction-fantasy film directed by Gil Kenan, which was based on the 2003 novel of the same name by Jeanne Duprau.

Plot

The movie introduction explains that the City of Ember is a fully-contained city built underground to house a human community for 200 years as a shelter from an unspecified disaster. A box has been provided which automatically opens after 200 years, and contains a tool and instructions for returning to the surface. Mayors of Ember keep the box a secret and only disclose its existence to their successors in office. When a mayor suddenly dies while still in office, the box ends up forgotten in a closet in a descendant's house and unnoticed by anyone when it automatically opens as designed.

Some decades later Ember's food supplies are becoming depleted and blackouts are increasingly frequent and longer-lasting, as the hydroelectric generator that powers the city has deteriorated. Much of the knowledge and technology from the city's near-mythic Builders and earlier generations has been lost.

Two young friends, Lina Mayfleet and Doon Harrow, who live in the City of Ember, are graduating from school. Lina is assigned to work in the Pipeworks of the hydroelectric generator, but trades jobs with Doon, who does not like his assignment to work as messenger. They begin their jobs with Lina as one of the messengers who run around the city to deliver communications following the collapse of the telephone system, and Doon as a technician in the Pipeworks. Lina witnesses the city's decay as she relays messages, and Doon learns that the Pipeworks are held together with increasing amounts of patchwork. Nobody knows in detail how any of the city's systems work. After a major malfunction of the generator during the city's annual celebration, Lina and Doon conclude that Ember is in danger of imminent collapse. With the city's adult population either largely ignorant of their plight or cowed by the corrupt Mayor Cole, Lina and Doon search for the clues left by the Builders showing the citizens of Ember how to save themselves.
Mayor Cole, understanding the gravity of the city's situation, has been stockpiling food in a secret bunker to guarantee his own survival. After discovering the bunker, Lina attempts to report Cole's hoarding but instead is brought to the mayor. He suspects that Lina, a descendant of the earlier mayor who died in office, may be in possession of lost secrets about Ember and orders her and Doon arrested.
Indeed, Lina has the box in her home and has begun to understand its importance. The pair escapes and try to find their way out of the city with the instructions left in the box by the Builders, and receive unexpected assistance from Doon's elderly mentor Sul. Meanwhile, Mayor Cole goes to his bunker and he is killed by a giant star-nosed mole. Arriving at the surface they are initially disappointed that it is dark there as well, as described in Ember's folklore, but when the sun rises they discover that light has returned to the skies and the planet has recovered. They also see through a hole the lights of Ember deep below the surface and realize they had lived in an underground city. Lina and Doon drop a message tied to a rock through the hole down to Ember telling the other citizens how to leave the city, where it is found by Loris Harrow, Doon's father and one of the few adults aware of the city's serious situation.

*It's not hard to understand the storyline, but it's just beyond our imagination about how people live 200 years before can plan so precisely. It's like a Nancy Drew's but with less actions and adventureous scene. Still, it's fun to watch.