On sabbatical in Rome, Dr. Richmond meets the volatile genius of the opera, Erik Costanzi. The chance to study the connections between madness and genius seem to converge in the exaggerated stories of Costanzi's eccentric life. When an accident strikes one of his children, Erik's emotional and violent reaction confirms the doubts that Dr. Richmond has planted in Meg's mind about her husband's sanity. Although she agrees to permit Dr. Richmond to treat Erik, she has no idea that the physician intends to take him out of the country to an undisclosed location to study him for an indeterminate period of time.

Taken by force from his home, believing that Meg has betrayed him, Erik is compelled to reveal his past as the Phantom of the Opera. But there are other memories and revelations that Erik has been unable to face that Dr. Richmond's sessions bring to the surface. How will Erik confront these secrets? How can he forgive Meg's complicity with the man who makes him face his darkest night?

A fifth book in the Phoenix of the Opera series, Phantom Madness returns to the same characters and continues the story of the Phantom of the Opera.