Charles Wesley Alexander wrote Angel Agnes shortly after the 1873 yellow fever epidemic that devastated Shreveport, Louisiana. The book is a heavily romanticized account of a young nurse named Agnes who came south to volunteer during the outbreak and worked alongside the doctors and clergy who stayed behind when most of the city had fled.
The book sits between memoir, hagiography, and Victorian sentimental fiction. Modern readers should approach it knowing the conventions of the period rather than expecting documentary precision.
That said, the underlying historical event is real and the book is one of the surviving popular records of it. The mortality figures, the abandonment of the sick by those who could afford to leave, and the work done by religious sisters and volunteer nurses all show up in the text.
For readers interested in nineteenth century epidemic literature or American medical history, this is a primary source worth reading carefully.