The 100

Cass Morgan’s The 100 (2013) is the first installment in a four-part series of young-adult dystopian novels. Through the experiences of four teenage protagonists, the story chronicles the efforts of a human space colony to recolonize Earth before oxygen levels on the space station drop too low to support life. Through an interwoven web of romantic relationships, friendships, personal trauma, and strife, the book explores the effect of oppression, the intersection of power and privilege, and the role of freedom in shaping identity. 

The 100 series is a New York Times bestseller and was also adapted into television series that ran from 2014 to 2020 and aired on the CW. Cass Morgan is the penname of American author and editor Mallory A. Kass, who is best known for writing The 100 series. She earned a bachelor’s degree in English and history from Brown University and a master’s degree in 19th-century literature from Oxford University. She now lives in New York City, where she works as an editor for Scholastic Press. The next three novels in The 100 series are Day 21, Homecoming, and Rebellion.

This guide is based on the 2013 e-book edition of The 100.

Content Warning: The source material and this guide feature depictions of cursing, child abuse, child death, death, death by suicide, animal death, sexual violence and harassment, pregnancy loss, addiction, and substance use.

Plot Summary

Several hundred years before the primary events of the novel, Earth was rendered inhabitable by the aftermath of a nuclear war known as the Cataclysm. In the narrative present, the descendants of humanity live aboard a space colony that is divided into three sections—the upper-class Phoenix ship, which is connected to two lower-class ships, Walden and Arcadia. The novel follows four teenage protagonists: Clarke, Wells, and Glass of Phoenix and Bellamy of Walden. On the space colony, only the ruling council and Wells (the chancellor’s son and Clarke’s former boyfriend) are aware that the colony will soon run out of oxygen. As a result of this imminent crisis, the leaders decide that 100 juvenile convicted criminals will be sent to Earth to find out if the planet is habitable enough for humanity to return.

Glass and Clarke have been convicted of breaking the Gaia Doctrine (the document governing population control and daily life aboard the space colony), so they are now among the 100 being sent to Earth. Clarke was convicted for aiding her parents with inhumane experiments on children; however, her sentence ignores the fact that the vice chancellor was forcing them to conduct these experiments. Glass was arrested when she became pregnant without permission. (The narrative reveals that she broke up with her boyfriend Luke to keep him from being implicated in the illegal pregnancy, thereby saving him from summary execution. She also lost the baby.) 

Because Wells has insider knowledge of the colony’s workings, he damages the airlock further, knowing that this will cause the trip to Earth to be expedited; his action ensures that Clarke will be put on the transport rather than being executed. He then commits a crime to get placed on the transport so that he can work on winning her back. (The narrative reveals that the two broke up after Wells unintentionally told his father about confidential information from Clarke, indirectly causing the arrest and execution of her parents.)

Bellamy is not slated to be aboard the transport to Earth at all, but he forces his way on board to accompany his sister, Octavia. In the process, Wells’s father is shot and incapacitated, leaving the corrupt vice chancellor in charge of the colony. In the commotion, Glass escapes the transport and goes to Walden to be with Luke, only to find that he has a new girlfriend. 

Meanwhile, the transport crash-lands on Earth, injuring many and killing a few of the teens. Because Clarke is the only one with medical training, she establishes herself as medic and treats the injured, including her best friend. Meanwhile, Bellamy becomes proficient at hunting and provides food for the group, while Wells tries to assert his authority as the chancellor’s son—only to be shunned due to the group’s disapproval of his father’s leadership.

Meanwhile, on the colony, Glass receives a full pardon from the vice chancellor and is expected to return to her high-society life on Phoenix. However, her time in prison has changed her outlook, and she now works to win back Luke. He softens toward her when he learns about the illegal pregnancy that led to her arrest. 

On Earth, Wells tries to reignite his romance with Clarke, but she blames him for the deaths of her parents and finds herself growing closer to Bellamy instead. 

While out hunting, Bellamy finds missing medical supplies that were thrown during the transport crash. When he shows them to Clarke, she is overjoyed, and the two kiss. Wells sees the kiss and vows to do whatever it takes to win Clarke back.

With the medicine, Clarke knows her friend will make a full recovery. However, the following day, the medicine is gone. The only three people who spent the night in the medical tent were Clarke, her unconscious friend, and Octavia. When Clarke confronts Bellamy with her suspicions that Octavia might be the thief, he is hurt that Clarke could think so little of his family. 

Meanwhile, Wells leads the others in confining Octavia, hoping that Clarke will appreciate his actions. Bellamy finds his sister’s hair ribbon tied around a tree branch far from camp and discovers that his sister took the medicine because she is addicted to it and struggles to sleep without it. After this incident, many want to execute her, but Wells convinces everyone that Bellamy and his sister should merely be banished.

One night, a few weeks after the crash landing, a comet passes close enough to be seen from both the planet and the space colony. Phoenix throws an elaborate party, but Glass leaves the festivities to be with Luke on Walden. Luke proposes, and Glass accepts. When he walks her back to Phoenix, the hallway linking the two ships closes off, trapping Luke in Walden and Glass in Phoenix. The colony’s oxygen levels have dropped to dangerous levels, and the council has decided to sacrifice Walden and Arcadia so that the people on Phoenix will have more time to live. Devastated, Glass crawls through a vent and returns to Walden to be with Luke.

Meanwhile, Clarke forgives Wells for his role in her parents’ executions. The two get lost in a kiss as the comet shoots through the sky, but they are distracted by the new crisis of a raging fire at camp. Clarke dashes to save her friend from the burning infirmary tent, but Wells pulls her back. As the flaming tent collapses, Clarke blames Wells for preventing her from saving the other girl. 

Octavia goes missing in the chaos. Clarke goes with Bellamy to search for her, and the two find an orchard of apple trees that are planted too uniformly for the arrangement to be natural. At camp, Wells leads clean-up efforts, which are interrupted by an attack from humans who have been living on the planet.