I knew this was fiction going in but there were still points I had to remind myself of the fact. It reads very much like a true crime book, especially when we get to trial transcripts. The whole thing is very, very readable even as we move between Roddy's personal account, court documents, court transcripts and other various pieces of documentation.
Roddy Macrae is charged with three murders and for most of the book you are reading Roddy's account of his growing up in the village and the events of that day. He admits his guilt and simply explains things as he sees it. Of course, all that is challenged in various ways by the trial, a criminal expert, and the people who watched him grow up. It's really a quite fascinating book and quite a lot of packed into 280ish pages.
It's very readable, at points sympathetic and unsympathetic, and certainly gruesome. Extremely believable overall as well.