I'd say that 3 stars if a fair rating for this book. First of all, it's almost like 2 separate stories. There's the historical narrative and the present day narrative.The historical is by far the stronger story and that makes this book lopsided. The medieval town is fully fleshed out and holds most of the book quite well.And that makes the present narrative all the more awkward. In terms of page count there is much less in the present. I don't know if it's the cause or effect of the two contemporary researchers having very little character but they come across as flat. With so little page time all they do is deliver lectures about their fields of study (history and physics). I would have loved for them to be less like a set of tools and more like the historical people who's plot wanders around their daily lives.Like most split narratives the stories come together towards the end of the novel. It wasn't until the last section that I realized the present narrative was really a detective story and should have been paced and plotted like one all along.Overall I'd say that this book is worth reading but still flawed.