Thomas Chaloner returns from an assignment in Tangier and almost immediately witnesses a murder. His pursuit of the killer draws him into a network involving stolen corpses, clandestine medical activity and planned attacks on senior officials.
The conspiracy eventually points towards Queen Catherine of Braganza, whom someone intends to frame for treason. Chaloner must identify the people manufacturing the evidence while working through a court where hostility to the foreign, Catholic queen gives the plot a ready audience.