Littrell decides to track down his maternal McDonald ancestors after some additional family papers turn up. He starts out in the most amateurish way imaginable: googling names. He proceeds through sending away for his own DNA test, visits to Scotland, looking at close matches online, asking other people to provide DNA test information, visits to cemeteries (including one on private land still owned by distant cousins), hiring other genealogists to do local research for him and paging through books of marriages, probate records and similar.
So half the book is the Making of a Genealogist, in a very modern sense: one who combines what we can get from paper with what we can get from blood to piece together a scattered history.
The other half of the book is the history of his branch of his clan, in particular, the events leading up to the massacre at Glencoe. The structure of the book alternates chapters of history with chapters of genealogical research and his own life progression (he gets married and honeymoons in Scotland, meets new found relations, etc.).
I did not read this because of any overlap in trees with Littrell; I bought it because I will eventually write my own genealogical memoir, and would like to understand how other people structure material to maintain reader interest (hey, it's _all_ interesting to me, but I know better than to think anyone else will feel that way), and I'm also curious about what kinds of family stories people believe can carry a memoir.
I'm not sure I would have finished the book, except for the fact that it was sitting on my kindle when I restarted an indoor exercise program (i.e. I read it on the treadmill). I also skipped a fair amount of the Scottish (Scots?) historical material. I think it might be more interesting to someone with a stronger interest in Clan Donald/MacDonald/Mcdonald/etc. I really liked the other half of the book, as Littrell did a really non-preachy depiction of how he got really good at being a careful genealogist, largely by doing genealogy.