Mary Sutter has been trained as a midwife by her widowed mother, and has demonstrated an unusual aptitude.  She is an eager learner, but her deepest desire is to be a surgeon.  No medical school will take her, however.  As reports reach her home town of Albany of the escalation toward civil war around Washington DC, and in the wake of a disappointment in love,  she decides to board a train and offer her services to Dorothea Dix as a nurse.  Though Miss Dix refuses her on the grounds of her youth, Mary finds her way into apprenticeship with a surgeon who, as the numbers of injured climb, needs all the hands he can get.  Slowly and grudgingly, he comes to accept her as a competent assistant and, eventually, to teach her as a respected apprentice, and the remarkable companion she has become to him.  She learns surgery in the most grueling circumstances possible, amputating shattered limbs of young men, many of whom die anyway of infection or water-borne diseases.  In the course of her sojourn in Washington she meets John Hay and, through him, President Lincoln, whose compassionate attention she manages to direct to the dire need for medical supplies.  Two men love her not only for her intelligence and courage, but for the passion she brings to the hard-won skill that, though it cannot save her brother from the respiratory illness that is rampant in the camps, or her sister from a disastrous childbirth, saves many lives and makes a wider way for women of her generation who find themselves called to medicine.