Excellent narrative nonfiction that covers the introduction of inoculation into London and Boston in the 1720s. Carrell follows two people—Lady Mary Worley Montagu in London and Dr Zabdiel Boylston in Boston—both survivors of bad cases of smallpox, both worried parents, both intense record keepers. Those records—letters, notes, case records—as well as official government minutes, newspapers, and the records of others—are fabulous sources.