London, 1679. A year has passed since the sensational attempt to murder King Charles II, but London is still a viper’s nest of rumored Catholic conspiracies, and of plots against them in turn. When Harry Hunt --- estranged from his mentor, Robert Hooke --- is summoned to the remote and windswept marshes of Norfolk, he is at first relieved to get away from the place. But in Norfolk, he finds that some Royal workers shoring up a riverbank have made a grim discovery --- the skeleton of a dwarf. Harry is able to confirm that the skeleton is that of Captain Jeffrey Hudson, a prominent member of the court once famously given to the Queen in a pie. Except no one knew Hudson was dead, because another man had been impersonating him.

The City of London, 1678. When the body of a young boy drained of his blood is discovered on the snowy bank of the Fleet River, Robert Hooke, the Curator of Experiments at the just-formed Royal Society for Improving Natural Knowledge, and his assistant Harry Hunt are called in to explain such a ghastly finding. Meanwhile, that same morning, Henry Oldenburg, the Secretary of the Royal Society, blows his brains out, and a disgraced Earl is released from the Tower of London, bent on revenge against the King, Charles II. Wary of the political hornet’s nest they are walking into --- and using scientific evidence rather than paranoia in their pursuit of truth --- Hooke and Hunt must discover why the boy was murdered and why his blood was taken.