The Book of Kells

Very interesting if you already know about Irish / Viking / Church history. I didn't, so it took me quite a long time to get into this book. There are a lot of references, tidbits, details and vocabulary that I had to work at.

(Discovered the Glossary only after reading).

When you can appreciate all those layers it is an excellent story, very entertaining, completely plausible (apart from the time travel, of course) and highly recommended.