In the city of Vienne in the land of Ile-Rien, master criminal Nicolas Valiarde discovers that his elaborate plans for revenge are being disrupted by the return of a supernatural menace from centuries past.

[1] Kirkus Reviews considered it to be "thoroughly engaging", with "splendid plotting and characters and agreeably varied magics".

[2] At SF Site, Steven H. Silver judged the plot to be "relatively simple", and in particular questioned the likelihood of Valiarde taking years to construct both a criminal empire and an entire separate persona as part of his planned revenge, only to be distracted at the last minute by the seemingly uninvolved Doctor Octave; Silver did, however, laud Wells for having created characters and a setting that "retain the readers' attention", and for avoiding a "comedy of errors" situation, ultimately stating that the novel was "worth reading".

[3] Wells has stated that her portrayal of Valiarde was based on her desire to "write a protagonist who in most books like this would be the antagonist, if not the outright villain.

"[4] The novel has a Sherlock Holmes theme, with Valiarde being based on Professor Moriarty, his assistant Reynard Morane being based on Sebastian Moran, his law-enforcement nemeses Inspector Ronsarde and Doctor Halle being based on Holmes and Doctor Watson, and his companion Madeline being based on Irene Adler ("but also Ellen Terry and Sarah Bernhardt").