The novel takes place in 1880s New York, in a slum district where cruelty reigns and people show neither compassion nor honesty. Una Kelly, a professional thief and con artist, survives in this merciless world by following her own rules. When she is mistakenly accused of murder, Una manages to escape and—under a different name—get into a newly created nursing school at Bellevue Hospital, founded with ideas of Florence Nightingale in mind. At first she has no intention of studying; she is simply hiding from being pursued. But working at the hospital gradually changes her, and she begins to show compassion and a capacity for self-sacrifice.