I’m not sure about the subtitle of “solving Europe’s ancient mystery”. It is a mystery, of course, and it’s comparatively ancient, but I don’t think Aldhouse-Green manages to solve it. Examine it closely and lay out what evidence we have, yes, but that evidence doesn’t convince me that we have enough to make real judgements about what was going on. Especially not because Aldhouse-Green’s book takes in bog bodies all over Europe — places that in many other ways haven’t been demonstrated to have similar beliefs.
The book is strongest when she sticks to the facts. If you’re fascinated by bog bodies, there’s a whole range of them discussed at length, both the forensics of their deaths and the items that were found with them, and even what we know now with modern science about their lives. Even if you’re with me in thinking that some of the theories lean too hard on supposing there are commonalities across huge breadths of space and time, there’s a lot to learn here.