The narrator of this tale of demonic seduction is a twenty-five-year-old Spanish soldier named Alvaro Maravillas who is a captain in the king's guard in Naples. He admits that his chief occupations, when he can afford them, are gambling and womanizing. One evening after he and his fellow officers had been sitting and drinking, an old Dutch soldier confides in Alvaro that he is a practitioner of the occult arts and has been able to summon an infernal spirit to be his personal servant. Of course Alvaro wants to try it himself.
In the ruins of an ancient temple, standing inside an inscribed pentagram, Alvaro repeats the incantation he has been taught to summon Beelzebub. A horrible and threatening visage appears, but Alvaro stands his ground and commands the demon to submit to him and prepare a feast for his companions, complete with a servant in livery. All is done as Alvaro has ordered, but the servant, a youth of striking beauty, looks at Alvaro in the most unsettling way. After the dinner the servant refuses to be dismissed or even leave Alvaro's side, and insists on becoming his page.
It isn't long before Alvaro confirms his suspicions that his page is actually a woman. He calls her Biondetta. She claims to by a sylph, an air-spirit, who fell in love with Alvaro and seized the opportunity to take human form to become his lover. She sets out patiently to seduce Alvaro who is naturally wary of such a being. Is she really a spirit become mortal as she claims to be? Or is she Beelzebub himself in disguise? Can Alvaro trust anything his senses tell him, or is everything he sees and feels just a grand illusion?
Cazotte's writing is remarkably fluid and concise for its time, more reminiscent of Poe than other 18th century authors. His handling of the apparent gender shifting of Biondetta--"she" in one guise, "he" in another--is subtle and eerie, as are the growing erotic tension and the uncertainty over Biondetta's true nature. The weakest part of the story, however, is its ending, which is abrupt and unsatisfying. According to Brian Stableford's introduction, Cazotte has originally planned (and perhaps wrote) a work twice as long, and the ending was rewritten because early readers rejected the author's first version. The Devil in Love is a captivating story that, with a better ending, would have become a classic.