England is rife with conspiracies to assassinate Elizabeth I and return the country to Rome—plots that foment in places like the fiercely papist University of Oxford. Giordano Bruno—renegade monk, poet, scientist, and magician—arrives in London, fleeing the Roman Inquisition. Bruno believes that the Earth orbits the sun, and this alone could have him burned at the stake, but he also seeks a lost book of ancient truth, which he believes will end the religious wars.
Bruno is recruited by Elizabeth's spymaster, Sir Francis Walsingham, and sent undercover to Oxford, but his mission is thrown off course by a series of grisly murders. Bruno suspects that the murderer is trying to send a message—but what and to whom? Stalking the killer through the shadowy cloisters of the colleges and back streets of Oxford, he soon learns that sometimes even the wisest men cannot tell truth from heresy.