The Second Sleep by Robert Harris
From Knopf Publishing Group:
From the internationally best-selling author of Fatherland and the Cicero Trilogy–a chilling and dark new thriller unlike anything Robert Harris has done before.
1468. A young priest, Christopher Fairfax, arrives in a remote Exmoor village to conduct the funeral of his predecessor. The land around is strewn with ancient artefacts–coins, fragments of glass, human bones–which the old parson used to collect. Did his obsession with the past lead to his death?
Fairfax becomes determined to discover the truth. Over the course of the next six days, everything he believes–about himself, his faith, and the history of his world–will be tested to destruction.