I found this second book even more adventurous than the first. I like the way the author leaves his characters on a knife edge at the end of some chapters, then reveals later how they plausibly extricate themselves from harm.
The locations in what is now northern Scotland was refreshing. The illustrations are first class and helped me better understand 7th century lifestyle. The comparisons between the Celtic Church and the Church of Rome may appear to be somewhat critical, but I presume it reflected the perceptions of that era.
Looking forward to Book 3.