Fifteen-year-old Rachel is furious and lonely when her father moves the family to Boston in 1872—especially since she had to sell her beloved horse. But in Boston she finds the Governor’s Girl, an injured firehorse, and begins caring for her and thinking about becoming a veterinarian. Then an outbreak of fires causes Rachel to question the ethics of her journalist father, and when the horses who pull the fire engines fall ill, the danger escalates. In a dramatic climax, the Great Boston Fire of 1872 is brought to life with cinematic vividness, and Rachel proves her grit and determination to make something of herself.