Herald - The Welsh Guard Mysteries, #4

Rhys and Catrin contend with betrayal and insurrection as they resume their duties in the king's court ... September 1284. Within moments of rejoining the king's company, Rhys and Catrin learn King Edward has not only melted down the silver seal of their murdered prince and turned it into a chalice, but the chalice itself has gone missing a matter of days before its intended consecration at Vale Royal Abbey.
Assigned to find the culprit, they discover instead a populace seething over the predations of the abbey and its officers, and an unusual alliance between Norman and Saxon. As the unrest in the countryside grows, Rhys and Catrin's initial apathy turns to urgency, and with Cheshire teetering on the brink of open rebellion, they are not the only ones who have to decide how much they're willing to sacrifice to bring down a king.
Herald is the fourth book in The Welsh Guard Mysteries. Series so far: Crouchback, Chevalier, Paladin, Herald