The Phantom of the Opera - Gaston Leroux
This is an oldie but a goodie and would make ...a great musical.
According to Wikipedia, the novel was first published as a serial, which explains the many, sometimes unnecessary twists and turns of plot. The story opens with the narrator recounting the mysterious death of a Comte, the disappearance, presumed death, of the Vicomte and the disappearance of opera singer, Christine Daae from the Paris Opera House. The pace of the novel is maintained by the drama of the Opera Ghost (is he a man? Or a phantom?) and the tension of the inevitably doomed couple.
While a product of its time, the attraction of the novel is really the descriptions of the Opera House, of the city-within-a-city. It was a great book to read when travelling through Paris, with its stratified society still present today.
And now I want to see the musical.