Saracen's mark is so detailed that it feels as though you are in the book walking the streets with these people. Based in the 16th century there is an unknown disease that is spreading through London and fear that it will cross the river and continue to wipe out the population. It's impossible to believe that something like this could happen now a days. The story moves between the streets of London and Marrakech where the physician Nicholas is sent on a mission by Robert Cecil the Queen's spymaster and the apothericarist Bianca continues to seek out the truth in London. There is so much going on in this story from murder to adventure it was a really gripping read. This is the third book in the series. I haven't read the other two and it can definitely be read as a stand alone book but read them in order if possible as I feel I missed out on some of the storylines. I will now read the other two in the series.