Dust is a 2013 novel by Hugh Howey, the third installment in the post-apocalyptic science fiction Silo trilogy. Dust centers on the lives of several people in different silos, enormous underground buildings intended to preserve humanity from the ravaged, toxic outside world. Each character fights to discover the truth about why someone trapped humankind in the silos as they try to survive the schemes of Silo 1, the creators of the silos and of the technology that wiped out the world in the first place.

Hugh Howey is a New York Times best-selling author known for his science fiction and young adult works. The Silo trilogy originated as self-published short stories and novellas that he eventually compiled and traditionally published in 2012. Other works by Howey include Shift and Wool.

This study guide refers to the Mariner Books paperback, an imprint of HarperCollins Publishers, published in 2016.

Content Warning: The source material contains graphic depictions of violence and death; it also discusses the sexualization of a child.

Plot Summary

In the future, humans live inside silos, enormous enclosed cities. The world outside the silos is toxic; those punished by being sent outside (the typical punishment for people who want to leave the silos) tend to die in minutes. Rebellions often happen inside the silos. When they do, the government of Silo 1 maintains control by killing the rebels remotely and doses the population with amnesia-causing drugs. The first two novels of the series reveal that the silos were activated 200 hundred years before the events of the novels, during a mid-21st-century nuclear war launched by a cabal of US Senators, in part because of terrorist groups deploying weaponized nanobots that were taking over the globe. The residents of Silo 1, however, are the still-living masterminds of the silo program: Women stay in cryofreeze, while men, including former Senator and nuclear war mastermind Thurman, wake from cryofreeze for cyclical six-month shifts to ensure their survival over centuries. In theory, it will take 500 years for the Earth to be habitable once more.

The novel opens after most of the population of Silo 17 has been exterminated for rebelling. In neighboring Silo 18, Mayor Juliette Nichols, the only known person to survive going outdoors, leads a team to break through the wall at the silo’s base, attempting to reach the survivors in Silo 17. In the process, Juliette’s team discovers a strange, gigantic machine on the other side of the wall and uses Silo 18’s generator to get it working. Silo 18 experiences mild unrest due to Juliette’s decisions. Meanwhile, survivors in Silo 17, including Jimmy and seven-year-old Elise, wait for their rescue.

In Silo 1, siblings Charlotte and Donald (one of the silos’ architects and thus key Silo 1 personnel) hide out and attempt to disguise their presence. In the previous novel, Donald realized that only one silo would be permitted to resettle the Earth; he is working to avert that plan and make sure that all remaining silo residents survive. When a young woman whose identity has purposely been scrubbed is found murdered in her cryopod, Thurman accuses Donald of being the culprit.

In Silo 18, Juliette holds a town hall and witnesses her people’s unease; she decides to go back outside to gather samples to assuage people’s fear. Just then, the digger breaks through to Silo 17. Silo 18 explores Silo 17 and brings the survivors back for medical treatment. The survivors are nervous and feel out of place; Elise finds and rescues a puppy. Meanwhile, Juliette gathers samples from the outside and brings them back, going through extensive sanitary precautions to prevent contamination. She and her lover, IT head Lukas, transport the samples to a lab, where she performs experiments and realizes with horror that the silos are pumping out the toxins making the Earth unlivable.

Juliette calls Silo 1 and confronts Donald, who realizes what she is describing: Destructive nanobots that attack human tissue have flooded the outside world; due to a venture outside, they are ripping apart Donald’s body. Soon after, Thurman brutally beats and arrests Donald, though his sister, Charlotte, escapes.

Silo 18 grows more uneasy and erupts in violent riots. Juliette attempts to calm the riots. Elise keeps going missing, much to Jimmy’s concern.

Thurman decides to remotely terminate Silo 18. As poisonous gas begins to seep out of the walls, Lukas tells Juliette to get people to Silo 17; after she manages to lead about 200 people through the tunnel, a friend sacrifices herself to seal off the tunnel and ensure their survival. Lukas dies in Silo 18’s IT department.

Charlotte listens to the destruction on the radio and decides to rescue her brother and try to save the silos. She successfully infiltrates Comms, but her attempts to communicate with the other silos are unsuccessful. Meanwhile, a soldier named Darcy investigates her victim’s death and deduces her identity.

Juliette stops the grieving survivors of Silo 18 from desperately trying to dig back to Silo 18 and decides to take revenge on Silo 1 using dynamite. Meanwhile, Elise meets Rash, a man who insists he can feed her if she comes to the chapel; she reluctantly agrees. In the chapel, Elise witnesses the brutal removal of a birth control implant from a woman’s leg and is forced to sign marriage documents binding her to Rash. Jimmy finds her and threatens Rash with a gun; she then takes her and her dog back to safety.

With help, Charlotte rescues Donald, who reveals that all silos have several methods of self-destruction, including Silo 1. They prepare to escape in hazmat suits, but Donald first goes to destroy Silo 1 and Thurman, exploding the silo behind Charlotte as she begins to trek across the barren land.

Juliette reaches the server room and discovers that the servers are a map pointing to Seed, a potential haven far beyond the silos. She decides to pursue life rather than revenge. Many survivors agree to join her, and they work together to upgrade the hazmat suits so they can walk overland to Seed. Juliette and the others walk overland and discover a safe, beautiful wilderness with a tower filled with supplies. Nanotechnology only affects the area around the silo, so they are free to settle the world as they see fit. Charlotte joins them. Juliette and Elise name constellations after Lukas and Elise’s puppy as the survivors plan their future.