Wiltshire, during the dying days of Oliver Cromwell's Republic. Robert Vaughan is the son of a Parliamentarian officer who is investigating a series of grisly murders which suggest a link with Satanic rituals at Stonehenge. The return of a notoriously wicked Cavalier, signalling the impending royalist restoration, leads to a terrible tragedy for the Vaughans. Robert's flight from his violent, terrifying past leads him to Restoration London, where he works as scribe for Milton, and where he survives the Plague and the Great Fire.