This novel serves as a prequel to
The City of Ember, set decades before the events of that book.
In Yonwood, North Carolina, a woman named Althea Tower collapses after a terrifying vision of blinding light, fire, and the earth consumed by flames followed by terrible silence. Her neighbor, Brenda Beeson, finds her, but Althea can only mutter about fire and disaster. When the president announces that talks with a hostile alliance called the Phalanx Nations have reached a crisis and war may be necessary, Mrs. Beeson connects Althea's vision to the looming threat. Word spreads, and nearly everyone begins calling Althea "the Prophet."
Eleven-year-old Nickie Randolph and her aunt Crystal drive from Philadelphia to Yonwood to prepare Greenhaven, the family house inherited from Nickie's deceased great-grandfather Arthur Green, for sale. The ongoing Crisis has closed trains and brought military roadblocks to the highways. Nickie's father left eight months earlier on a secret government job, and the family has received only vague postcards from him. Nickie hates her lonely life in Philadelphia and sets three goals: keep the house from being sold, fall in love, and do something helpful for the world.
On Greenhaven's third floor, Nickie discovers Amanda Stokes, a frightened 17-year-old who cared for Arthur Green before his death, hiding in a closet with a small stray dog named Otis. Amanda has nowhere to go, so Nickie agrees to keep her secret and helps soundproof the nursery so Otis will not alert Crystal, who dislikes dogs.
A break-in at a local café, where a smashed window and bloodstained cloth are discovered, heightens the town's anxiety. Mrs. Beeson, who leads the committee interpreting the Prophet's mumbled words, suggests the stain is a letter standing for "sin," and talk of a terrorist in the nearby woods spreads. She arranges for Amanda to become Althea's live-in caretaker and tells Nickie to watch for "trouble spots," meaning sinners and signs of wrongness. The Prophet's influence is everywhere: a daily phone hotline, a ban on singing and pop music, and a mysterious humming sound whose source no one will explain.
With Amanda gone, Nickie secretly cares for Otis, growing deeply attached. She reads Arthur Green's notebook, which references extra dimensions and alternate universes. Postcards from her father arrive with hidden numbers in the postscripts.
A local boy named Grover Persons secretly keeps two snakes in a locked shed and dreams of attending a wilderness reptile expedition. One night, while retrieving a dropped notebook from the property of Hoyt McCoy, a reclusive neighbor, he sees a bluish glow behind the windows and a brilliant line of light shoot across the sky, as if the night cracked open.
Scouting for trouble spots, Nickie peers through Grover's shed window and sees him handling snakes. She reports this to Mrs. Beeson, embellishing by claiming she saw ghostly shadows around Hoyt McCoy's property. Later, she approaches Hoyt's house on her own, mistakes his telescope for a gun barrel, and flees. Mrs. Beeson calls the police, who confront Hoyt with drawn guns only to learn the object is a telescope. Hoyt denounces Mrs. Beeson for sending spies.
Mrs. Beeson escalates enforcement, delivering blue envelopes ordering people to change their behavior or face humming bracelets, unremovable metal bands that emit a constant noise and isolate the wearer. Grover receives a letter ordering him to give up his snakes and confronts Nickie when he learns she reported him. He tells her she should think for herself rather than taking someone else's word for what is right.
Guilt-stricken, Nickie visits Hoyt to apologize. Hoyt, in a generous mood after a successful "tense encounter," invites her inside. When he flips a switch, the walls and ceilings glow midnight blue, studded with stars, transforming the rooms into a model of the night sky. He explains that the heavens are his "habitat" and his job, though he will not elaborate.
Studying her father's postcards, Nickie cracks the code: The numbers spell C-A-L-I, revealing he is in California. She and Crystal prepare Greenhaven for an open house with Len Caldwell, the town's real estate agent, and a couple makes an offer on the property.
The president's deadline for the Phalanx Nations passes with no announcement, only silence. Mrs. Beeson summons the town and declares a new interpretation: "No dogs" means all dogs must be surrendered, because love given to dogs should go to God. Buses will collect every dog and release them in the wilderness. Most of the congregation accepts with grim resolve; Nickie is horrified but reassures herself that no one knows about Otis.
Two men ambush Grover and snap a humming bracelet onto his wrist. He flees into the mountains, where he encounters a large cream-colored albino bear. Grover realizes this is the figure townspeople called a terrorist and that it likely broke the café window while foraging.
The morning the dog buses arrive, Nickie comes home to find Amanda holding Otis. Amanda has reported the dog to Mrs. Beeson, believing the sacrifice is necessary. Nickie tries to wrestle Otis away but fails; Amanda hands the dog to a man loading the bus. Crystal returns and drives after the buses, but they have already turned around, emptied, and the dogs have scattered into the snowy woods.
Amanda returns briefly to say she found her own name on Mrs. Beeson's list of "sinners" and is leaving town, mentioning she left Althea alone. Nickie runs to the Prophet's house, finds Althea in bed, and shakes her arm. Gradually, Althea awakens and explains the truth: Her words described what she saw in her vision, not commands from God. "No sinnies" meant "no cities." "No lights" meant lights were gone, not forbidden. "No dogs" meant the absence of dogs in the ruined world. "No words" was "no birds." Althea is devastated to learn how Mrs. Beeson misinterpreted her.
As Nickie leaves, she hears barking. A pack of dogs comes bounding down Main Street, having found their own way home. Nickie finds Otis under a picnic table, muddy and full of burrs. Althea walks slowly down the street, frail but determined, and takes Mrs. Beeson aside to explain the truth. Nickie declares she is keeping Otis.
Before leaving Yonwood, Nickie secretly sells a valuable photograph from Greenhaven to fund Grover's reptile expedition. A letter from her father confirms he is in California and invites the family to join him. Nickie and Crystal depart with Otis. None of her three goals turns out as she expected, but she realizes she has fallen in love after all, with the dog.
An epilogue reveals that Crystal and Len, the real estate agent, marry and move into Greenhaven after the buyers withdraw, fulfilling Nickie's first goal unexpectedly. Grover becomes a renowned herpetologist, or reptile scientist, whose discovery of a painkilling chemical from a rare snake accomplishes Nickie's third goal. Hoyt McCoy hints his work astounded people in Washington, possibly helping avert war. Althea asks people to stop calling her the Prophet, though she never fully recovers her health. Decades later, global war threatens again, just as Althea's vision foretold. Nickie, now 60, volunteers to enter an underground city built by the secret government project her father worked on, connecting this prequel to the settlement that will become the City of Ember.