I just started reading The Poyson Garden by Karen Harper. Its a fiction book but it features histoical characters such as Eliszabeth I. Its set during the reign of Queen Mary I, otherwise known as Bloody Mary, while Elizabeth is exiled at Hatfield House. Elizabeth is called on by Mary Boylen to come see her on her death bed, and help her son find out why someone is trying to murder the last of the Boylen's.
I haven't gotten to far in the book as I only got it today...but I cant put it down!