March 1681. Oxford is hosting the English Parliament under the 'merry monarch', King Charles II. As politicians and their hangers-on converge on the divided city, an MP is found murdered, triggering tensions that threaten mayhem on the streets.

Luke Sandys, Chief Officer of the Oxford Bailiffs, must solve the crime and thwart the plot. On his side is the respect for evidence and logic he absorbed in his student days, as a follower of the new science. On the other, a group of political conspirators are stirring up sectarian hatreds in their scheme to overthrow the Crown.

Struggling to protect all he holds dear, Luke leans heavily on his cavalry officer brother, his friends, and his faithful deputy, Robshaw. But he has a secret, which may be clouding his judgement. At the moment of truth, will he choose love or duty?