Holliday, a thirteen-year-old girl living in a place with sharp class divisions, notices a new shop advertising "surgical augmentation of the character" on her way to get a gift for Molly, her younger sister. An apprentice convinces her to come in for a free consultation, and she is immediately berated by one of the doctors for being a mudlarker, or part of the lower class. Dr. Mortleaus makes fun of mudlarkers for having grand ideas of living in real houses someday rather than the sewers, and Holliday tells him that she thinks a revolution is possible. However, the main doctor, Dr. Svartlebarrt, enters the room, tells Mortleaus to calm down, and says they will give Holliday a free examination. They find that Holliday has extraordinarily excellent character and Svartlebarrt offers her a job. Holliday is thrilled—she's never done paid work before—and keeps her job a secret from her mother and uncles so she can get more gifts for Molly. Holliday learns everything there is to know about the surgery, which involves inserting marble-like "augmentations" into people's bodies. Each type of augmentation has a separate jar, and there's one mysterious jar that is never used. One day, Holliday's mother starts yelling at Molly for having a new toy, which she assumes Molly has stolen. Holliday comes clean about her job, but her family doesn't believe her, and they threaten to cut off Molly's hands. Holliday takes Molly and they run to the surgeon's shop, where Holliday begs Svartlebarrt to give Molly a job as well because her own wages aren't enough for them to survive. Svartlebarrt agrees to do an examination, but the doctors tell Holliday that Molly is of poor character and they can't hire her. Desperate, Holliday asks if they can do a surgery to make Molly good enough, and they refuse. However, they say there is one thing they can do—use the mysterious augments. At first Holliday says no because she wants to know what they will do, but she quickly realizes this is her only good option. While the doctors leave to get their equipment from the other room, Holliday grabs augments from the other jars and puts them in a layer on the top of the mysterious augments, hoping this will fool the doctors. However, when they come back into the room, they pin Holliday down next to Molly because it's a rare opportunity that they get to experiment on siblings. Mortleaus appears genuinely sorry, but tells Holliday he has been double-augmented with obedience and he has to do Svartlebarrt's bidding. When Holliday wakes up, she feels a rush of anger and heroism, and she attacks the doctors. Svartlebarrt yells at Mortleaus for using the wrong augments, and Holliday demands that they remove the augments from Molly. Mortleaus tells her it's too late, and Molly wakes up making inhuman sounds. Holliday grabs a scalpel and starts cutting the doctors, reflecting that anger is how revolutions begin.