The Eagle in Green Man's Clearing 

What should be done if there is horrifying evidence of human sacrifice in Gosbecks? 
That is the question the main character Quintus Agricolanus has to answer in the book The Eagle In Green Man’s Clearing.  Taking place in the first century AD Britannia. It chronicles the settlement of a  Roman Colonia for retiring Roman soldiers in Gosbecks, a real historical place which is located in present-day Colchester, United Kingdom.
The Romans came into Britannia with one mission which was to settle their people and add Britannia to their ever-expanding empire.  They did this by entering into treaties with the various Celtic tribes in Britannia.  The treaties were heavily slanted towards the Roman government and frequently levied unrealistic taxes on the indigenous populations. 
The other group of disconten
ted Celts was the Druids.  The Druids were the religious leaders in their communities and often acted in judicial roles or acting as the arbitrator in disputes.
.One branch of Druids was the healers for the villages and towns. 
The Romans saw the Druids as a source for potential problems in governing.   With the additional impetuous of human sacrifice, the Romans wanted to stamp out this priestly class. 
The Romans went in and immediately destroyed the Druid’s main bastion of their religion located on the Isle of Mona where the leaders of the Druid religion taught and ruled Britannia.  The Druids that escaped the battle went out into the countryside and spread the word to the remaining Druids in the countryside.