Nequam, a young boy, is discovered by talent seekers from Itrim, an Order dedicated to the learning of magical and scientific lore, because of his natural talent and extraordinary knowledge of mythology. Eridanus is a young shepherd who lives near Itrim. He regularly helps a student of magic there. The Lore- Masters soon find out about this and, amazed at Eridanus' talent, they take him up to Itrim. Nequam and Eridanus quickly become best friends, and Itrim's best students. They are the youngest people ever to be promoted to the rank of Lore-Master, and excel at all they do.

Nequam believes there is more to the myths than meets the eye, and after years of research reaches the conclusion that the myths are in fact true. If that is so, then Brogan, the great scientist, must still be alive (the story of what really happened to Brogan is related in Sentinel of Fate). However, Nequam thinks that Brogan must not be in Calaspia, but rather in the Spiritworld. Nequam determines to find out. Taking a huge gamble, he travels there with his spirit, abandoning his body and entering a shadowy world of supernatural beings whom he meets. After searching for what appears to be a very long time, Nequam finds him - or rather, Brogan finds Nequam. At this stage, the Order of Itrim becomes aware that Nequam is doing something forbidden by entering the Spiritworld. They offer him his life if he stops, but he is unwilling to do so having discovered the truth about Insanity. He tries to persuade them of his discoveries, but they cling stubbornly to the rules, and do not listen. For: "anyone who enters into collaboration with Insanity is surely corrupt, and must be put to death".

At this time Eridanus is on a different continent supervising research, and is unaware of what has happened until he returns. He gets the Lore-Masters' side of the story and is embittered. Nequam flees for his life to the south, where he rebuilds the fortress around the Pinnacle of Insanity and allies with the Nurgor to guard it. He activates the portal that Brogan mentioned and legions of Ostentum from around the globe are summoned to his fortress. He uses the powers of Insanity to control them (see Sentinel of Fate).

Then Nequam locks himself in his room in the heart of the Pinnacle, puts his body under special conservation attached to life-support systems, and enters the Spiritworld again, this time for longer. Brogan advises Nequam to send Ayactan to Calaspia to command his troops during his spirit's absence and protect his inanimate body. Whether Brogan was mistaken and thought Ayactan was faithful, or whether he just didn't care, is not known.

The book ends with Nequam in the Spiritworld being instructed by Brogan in how to destroy Insanity.