The Druid's Daughter by Ross Richdale

It is 320 AD and Hadrian's Wall separates Roman Britannia Inferior from the free lands to the north where the village of Darbarri is located. There, Jelena is asked by her father, Druid Floyd to travel south of the wall to help the people in the small village of Bramfield. It is a dangerous area for the new Roman emperor has declare that everyone should be forced to become Christians.