The proto-decadent short novel Isis was the first published prose composition of Auguste de Villiers de l'Isle Adam, and has only recently been translated to English by Brian Stableford. Although the author's dedication claims that the title "is the collective formula of a series of philosophical novels" projected to be written, none further followed, and "Isis" clearly alludes to the principal character Marchesa Tullia Fabriana.

It is noteworthy the extent to which this nineteenth-century work (set in the late eighteenth) anticipates and rehearses the tropes of the eventual modern superhero formula. Tullia is preternaturally learned, mystically initiated, and a superlative swordswoman. She has a trusty assistant/protege (recruited from orphaned destitution) and a secretly splendid headquarters. She routinely journeys out at the dead of night to aid the afflicted and heal the sick, under the anonymizing cover of a mask and specially-designed armor.

Unlike later crime-fighting capes tales, this book seems mostly unconcerned with plot, or at least fails to advance one very far. Short as it is, it indulges in some fine architectural description, anatomies of altered states of consciousness, and philosophical digressions. The style is reasonably abstruse, and its matter should be welcomed by those readers willing to tackle and appreciate classics of occult fiction such as Zanoni and Seraphita.

In the traditional Rosicrucian grade system, Tullia seems to be a rather accomplished Exempt Adept, perhaps a Babe of the Abyss. Her advancement to the grade of Master of the Temple in these terms would then be bound up with her encounter of the main viewpoint character Count Strally, a promising young man of parts who seems ready to accept her guidance.