The following version of the book was used to create this study guide: Barnhill, Kelly. When Women Were Dragons. Penguin Random House, New York, NY. 2022. AZW file.

Alex Green is 4 years old when she sees her first dragon in the yard of the woman next door. She quickly learns she is not supposed to talk about the experience. Soon afterward, her mother Bertha returns home from the hospital after being treated for cancer. Bertha's sister Marla has been caring for Alex during Bertha's illness. Marla remains a fixture in the home as Marla recovers. George, Alex's father, is often away on business. He soon spends even more time away from home. As Bertha recovers, she grows impatient with Marla. While Bertha has a college degree in mathematics, Marla works as an auto mechanic. One day, Bertha says Marla is not welcome unless she begins living a “normal life.” Marla marries and has a child named Beatrice. Though her husband is a drunken disgrace, Bertha welcomes her sister back.

There have been cases of women becoming dragons throughout history. Dr. Henry Gantz devotes a lot of time to the subject until the government shuts him down. Then, he spends time doing research in secret, much of it with the help of librarian Helen Gyzinska.

On April 25, 1955, more than a half million American women become dragons. Many of them devour cheating husbands on the spot. Despite the massive impact, the government censures information on the subject. Alex is in school during those hours. She obeys her teachers, keeping her eyes on her paper despite the sound of sirens and the smell of smoke. That afternoon, Bertha goes out. She discovers that Marla is among the women who dragoned that day. She returns with Beatrice. She decrees that no one will ever again mention Marla and that Beatrice is now her daughter and Alex's sister. They will continue this way until Bertha dies of cancer when Alex is just beginning high school. Alex's father George moves Alex and Beatrice to an apartment of their own. He provides financial support but nothing else. Alex is devoted to Beatrice though their lives are difficult. She finds herself always in the role of Beatrice's mother, and she begins to struggle with the idea that Beatrice will become a dragon and will also leave.

When Alex is a senior, the dragons begin to return. Alex immediately recognizes Marla but resists allowing Marla to become part of her life again. On the night of her senior prom, Alex watches as several girls dragon. This is again part of a bigger event. Since so many of these are young girls, the reaction is at least slightly different. They do not leave. They remain, demanding to pick up their lives and education. Social attitudes slowly begin to change. As a college freshman, Alex lives in a converted warehouse with Beatrice and four dragons, including Marla. Alex gives in to Beatrice's desire to become a dragon. Alex cites the changes that take place over the next two decades, including that Beatrice wins the Nobel Peace Prize for founding an organization that has literally put an end to those who depend on war as a means of control. As the novel ends, Alex is looking back on her life, including the woman she loved and her changing roles.