The Earl of Northumberland dismisses his hot-tempered servant, Tom Quill, with his two sons Nicholas and Peter, the latter just seriously injured. Life in London means death from smallpox for the father, no improvement for the demented Peter; eleven-year-old Nicholas takes his brother to the wizard of Mortlake for help. There Peter, never cured, becomes a ""scryer"" for the elderly astrologer and Nicholas becomes his apprentice, getting an education and carrying messages to the' highest-born of England. He records Elizabeth Tudor's declining years, the start of King James' reign, the Gunpowder Plot. The ending leaves things unaltered--the household at Mortlake to continue its stargazing, Peter to remain forever incurable. Research is evident in the vivid portraits of the important personalities of the court, but too much heavy-handed exposition slows the action. Less intricate than in many historical novels, the plot concentrates on Nicholas and fails to involve the other very interesting characters significantly. Add the insistently sixteenth-century dialogue, and you have a slow-moving slow-mover.