I am now reading this fascinating book and while it is not about Melungeons specifically, much of it is applicable. And the author does mention Melungeons on three pages in a much better and more accurate assessment than is usually accorded.
The author contends that there are millions of American who have no clue they have one or more African American ancestors. This phenomena is due to most families who got "white enough" choosing to pass for white. The social, legal and financial benefits were just too tempting to do otherwise.
Three families are traced in this book; the Walls, Gibson/Gipsons, and Spencers with information about allied lines. Modern day descendants are interviewed. One man only learned of his origin through extensive Genealogical research.
This is a well researched and written treatment. The author is very fair and impartial. His detailed descriptions of Civil War battles are worth reading the book for. If an officer made stupid mistakes and needless sacrifices of his men, this author states so regardless of which side that officer represented. This carries over into much of the retelling of historical events. And at the end of the day you come away with the understanding that these people were first and foremost human beings, mothers and fathers, doing their best to survive and make a better world for their children.