The Crown by Nancy Bilyeau has been described as a cross between Philippa Gregory and Dan Brown (Library Journal) and that is not far off.
The protagonist, Joanna Stafford, is a novice Dominican nun during the turbulent times of King Henry VIII. His first divorce is history and the dissolution of many monasteries has begun. Those who oppose the new religion, thereby opposing the king, are branded as traitors.
Joanna's cousin, Margaret, is to be burned at the stake as a traitor, and Joanna leaves the priory (without permission) to attend the burning and pray for her cousin. Unbeknownst to her, Joanna's father is also there.
When both are taken to the Tower of London and imprisoned there, Joanna is given a way out. She must find the crown of an ancient Saxon king, Athelstan, and give it to Stephen Gardiner, the Bishop of Winchester.
Joanna is troubled by many things. Her main concern is whether Gardiner's motives are really to help the church (Catholic) or simply to get more power. He has proven himself a violent person when he had her father tortured on the rack so as to persuade Joanna to undertake the task of finding the crown.
Read the whole review at: http://www.examiner.com/book-in-national/the-crown-by-nancy-bilyeau-review