The main characters are Lina Mayfleet and Doon Harrow, two 12-year-olds who watch as the light of Ember flickers and race to discover a way out.

Plot summary

Ember is a completely self-contained, self-maintained city. All food and supplies come from giant warehouses under the city and a handful of greenhouses. All the books in the library, apart from the city history “The Book of Ember”, “The Book of Letters” and “The Book of Numbers”, have been written by hand by residents over the years of Ember. Most curiously, all the light in the city comes from lamps and floodlights; when these are extinguished, the city is completely dark, with no stars, sun, or moon. The electricity in the city comes from an ancient hydro-electric generator in the underground Pipeworks; keeping the aging generator operational is a constant task. Beyond the borders of Ember are the dark Unknown Regions, which are unexplorable.

The story begins with two of the Builders, creators of Ember, discussing what will happen after things in Ember start getting bleak. They decide to leave instructions for escape in a special sealed box, which will open automatically in 220 years, when it will be safe to leave the city. The box is entrusted to the Mayor of Ember, who passes it down to the following Mayor when she leaves office. While the Mayors do not know what the box contains, they keep it safe over the years and do not tell anyone about it. However, the box is lost and forgotten when the seventh Mayor unsuccessfully tries to open it in order to cure his terminal disease, and then dies before he can pass it on to his successor.

The action then shifts to the year 241 in Ember. It is Assignment Day at the Ember school. On this day, the 12 year olds finish their education and enter the workforce. They are assigned jobs at random by drawing pieces of paper from a bag held by the mayor. One student, Lina Mayfleet, draws the job of Pipe-works Laborer; which will require her to work underground in the huge Pipeworks that power Ember and deliver its water, repairing lights and pipes as needed. Another student, Doon Harrow, becomes a Messenger, a job that involves running around Ember to deliver personal messages. Both Lina and Doon dislike their chosen jobs, and decide to switch.

Doon wishes to work in the Pipeworks because he is seriously concerned with the state of the city. Blackouts and power outages are becoming common in Ember. In addition, supplies are dwindling, buildings are crumbling and the city seems to be breaking down piece by piece. On the job in the Pipeworks, Doon explores the tunnels and tries to discover a way to save Ember. He even sneaks into the room containing the giant Generator, but realizes at once that he has no idea how it works, much less how to repair it.

Lina is thrilled to have the job of Messenger and works hard, puzzling over secret messages passed to the Mayor from a strange man named Looper.

Lina’s little sister, Poppy, discovers an ancient piece of paper in a box in their apartment. By the time Lina manages to pry it out of the toddler’s hands, the paper has been chewed and torn to pieces, and the writing has been obscured in many places. Lina hangs on to the scraps, and becomes convinced they hold a special message. She shows the paper to certain friends and neighbors, including her old classmate Lizzie Briscoe, but nobody has any clues as to its significance.

Eventually, Doon and Lina piece the paper together and discover that it includes “Instructions for Egress”–instructions to leave Ember. They descend into the Pipeworks and discover that the instructions are indeed valid, and that the underground river holds the key to escape from the city. They also discover that the Mayor is stealing the disappearing resources of Ember from the storerooms. They report the Mayor’s theft to City Hall, confident that he will be arrested.

However, the Mayor sets his guards upon the pair, and orders their arrest for “spreading vicious rumors.” Before they can tell the residents of Ember about the Instructions for Egress, they are forced to flee the city. Lina manages to take her little sister Poppy, and, with Doon, goes down into the Pipeworks and flees Ember by boat on the underground river.

The river eventually leads to a great rock slope. Poppy discovers a book on the riverbank; Lina and Doon keep it and bring it along to read later. After a long and arduous climb, Lina, Doon and Poppy emerge from the rocks into a new world, where they discover sunlight, moonlight, stars and nature.

This discovery is followed by another one, their history. The battered book turns out to be a personal journal; reading it, Lina and Doon discover that their city was founded by a group of one hundred adults and the same number of children as a measure to guarantee the survival of the human race in a disaster that obliterated civilization.

Doon and Lina discover a nearby cave. Looking down from a high cliff in the cave, they are amazed to see Ember below them–and realize that they have been living underground all along. In a last-ditch effort to save their city’s citizens, the three write a note with the Instructions for Egress, wrap it in Doon’s shirt, and hurl it down into Ember. It is found by Lina’s guardian, Mrs. Murdo.

Sequels

A sequel to Ember, entitled The People of Sparks, was published in 2004. Sparks picks up the story where Ember ends, and depicts the Emberites’ encounter with an aboveground town, Sparks, which was established after the Disaster.

A third novel, The Prophet of Yonwood, was released in the United States on May 9, 2006. While it is billed at the third installment of the “Book of Ember” series, the novel is a prequel, rather than a sequel, to Ember and Sparks, and is set fifty years before the Disaster and the establishment of the City of Ember.

A fourth novel, according to Jeanne DuPrau’s website, is in the works, but is not expected out for “a while”(estimated late 2008). An excerpt from the book, posted on her personal website, seems to indicate that the fourth book will pick up where The People of Sparks left off, during the Emberites’ first winter aboveground.

Film adaptation

A film adaptation of the novel is in development with Walden Media. Actor Bill Murray is attached to the project, which is slated to begin filming in summer 2007. City of Ember is slated for an October 10, 2008 release.