The narration is conducted on behalf of a young Spanish nobleman who almost fell victim to devilish machinations. When don Альlvar Maravillas was twenty-five years old, he served as captain of the guard of the King of Naples. The officers often indulged in philosophical conversations, and once the conversation turned to Kabbalism: some considered it a serious science, others saw it as only a source for tricking and deceiving the gullible. Don Alvar was silent and kept an eye on the eldest of his colleagues - the Flemish Soberano. As it turned out, he had power over the secret forces. Alvar wished to immediately join this great science, and to the warnings of the teacher frivolously answered that he would tear the prince of darkness from his ears.
Soberno invited the young man to dine in the company of his two friends. After the meal, the whole company went to the ruins of Portici. In a cave with a vaulted ceiling, the Fleming man drew a circle with a cane, inscribed some signs in it and named the formula for the spell. Then everyone went out, and don Alvar was left alone. He was not at ease, but he was afraid to pass for an empty fanfare and therefore complied with all the instructions, three times calling the name Beelzebub. Suddenly, a window opened beneath the arch, a flood of blinding light surged, and the disgusting head of a camel with huge ears appeared. Gape, the ghost asked in Italian: "What do you want?" Don Alwar almost lost his senses at the sounds of a terrible voice, but managed to control himself and spoke in such an imperious tone that the devil was embarrassed. Don Alwar ordered him to appear in a more appropriate appearance - for example, in the form of a dog. Then the camel stretched its neck to the very middle of the cave and spat out on the floor a small white spaniel with silky hair. It was a bitch, and the young man gave her the name Biondetta. By order of Alvar, a rich table was laid. Biondetta first appeared in the image of a virtuoso musician, and then - a lovely page. Collected and his companions could not hide their amazement and fright, but the bold confidence of the young officer somewhat reassured them. Then a magnificent carriage was brought to the ruins. On the way to Naples, Bernadillo (that was the name of one of Sobrano’s friends) suggested that don Alvar made an amazing deal because he had never served anyone with such courtesy. The young man said nothing, but felt a vague alarm and decided to get rid of his page as soon as possible. Then Biondetta began to cry out for a sense of honor: a Spanish nobleman cannot expel even a despicable courtesan at such a late hour, not to mention the girl who sacrificed everything for him. Don Alwar conceded: having refused the services of an imaginary servant, he undressed and lay down, but his face seemed to him everywhere - even on the canopy of the bed. In vain he reminded himself of an ugly ghost - the abomination of a camel only set off the charm of Biondetta.
From these painful thoughts the bed broke and the young man fell to the floor. When a frightened Biondetta rushed to him, he ordered her not to run around the room barefoot and in one shirt - so not to catch a cold. The next morning, Biondetta admitted that she fell in love with Alvar for the valor shown in the face of a terrible vision, and took a bodily shell to connect with her hero. He is in danger: the slanderers want to declare him a necromancer and give him into the hands of a famous court. Both of them need to escape from Naples, but first he must pronounce the magic formula: accept the service of Biondetta and take it under his protection. Don Alwar muttered the words prompted to him, and the girl exclaimed that she would become the happiest creature in the world. The young man had to come to terms with the fact that the demon assumed all travel expenses. On the way to Venice, don Alvar fell into a kind of numbness and woke up already in the apartments of the best hotel in the city. He went to the banker of his mother, and he immediately handed him two hundred guards, which Don Mencia sent through the equestrian Miguel Pimientos. Alvar opened the letters: the mother complained about her health and about filial inattention - but she did not say a word about money, out of her usual kindness.
Relieved to return Bondette's debt, the young man plunged into a whirlwind of urban entertainment - he tried in every possible way to be away from the source of his temptation. Don Alvar’s passion was a game, and everything went well until happiness changed him - he lost to the ground. Biondetta, noting his chagrin, offered her services: reluctantly, he took advantage of her knowledge and applied one simple combination, which turned out to be unmistakable. Now Alvar was always with money, but the anxious feeling returned - he was not sure that he would be able to remove the dangerous spirit from himself. Biondetta constantly stood before his eyes. To distract from thoughts about her, he began to spend time in the company of courtesans, and the most famous of them soon fell in love with him madly. Alvar sincerely tried to answer this feeling, as he longed to free himself from his secret passion, but everything was in vain - Olympia quickly realized that she had a rival. On the orders of a jealous courtesan, Alvar’s house was monitored, and then Biondetta received an anonymous threatening letter. Alvar was struck by the folly of his mistress: if Olympia knew whom she was threatening with death! For an incomprehensible reason for himself, he could never call this creature a true name. Meanwhile, Biondetta clearly suffered from Alvar’s inattention and poured out her longings in musical improvisations. Having overheard her song, Alvar decided to leave immediately, for the obsession was becoming too dangerous. In addition, it seemed to him that Bernadillo, who had once accompanied him to the ruins of Portici, was watching him. Porters carried Alvar's things to the gondola, Biondetta followed, and at that moment a masked woman stabbed her with a dagger. The second killer pushed the taken aback gondolier with a curse, and Alvar recognized the voice of Bernadillo.
Biondetta was bleeding. Beside himself with despair, Alvar cried out for vengeance. A surgeon appeared, attracted by screams. After examining the wounded, he announced that there was no hope. The young man seemed to have lost his mind: the adored Biondetta was the victim of his ridiculous prejudice - he took her for a deceptive ghost and deliberately put him in mortal danger. When the exhausted Alvar finally fell asleep, he dreamed of a mother: as if he was going with her to the ruins of Portici, and suddenly someone was pushing him into the abyss - it was Biondetta! But then the other hand caught him, and he found himself in the arms of his mother. Alvar woke up gasping with horror. Undoubtedly, this terrible dream was the fruit of a frustrated imagination: now there was no doubt that Biondetta was a creature of flesh and blood. Alvar vowed to give her happiness if she did survive.
Three weeks later, Biondetta woke up. Alvar surrounded her with the most tender care. She quickly recovered and flourished every day. Finally, he dared to ask a question about the terrible vision in the ruins of Portici. Biondetta claimed that it was a trick of the necromancers who intended to humiliate and enslave Alvar. But the sylphs, salamanders and Undins, delighted with his courage, decided to support him, and Biondetta appeared before him in the form of a dog. She was allowed to accept the body shell for the sake of union with the sage - she voluntarily became a woman and found that she had a heart that completely belongs to her lover. However, without the support of Alvar, she is doomed to become the most miserable creature in the world.
The month passed in delightful bliss. But when Alvar said that for marriage he needed to ask for a maternal blessing, Biondetta fell upon him with reproaches. The dejected young man decided nevertheless to go to Extremadura. Biondetta caught up with him near Turin. According to her, the villain Bernadillo became bolder after Alvar’s departure and accused her of being an evil spirit, guilty of abducting the captain of the quarter of the King of Naples. Everyone in horror turned away from her, and with great difficulty she managed to escape from Venice. Alvar, full of remorse, still did not abandon the idea of visiting his mother. Everything seemed to hinder this intention: the carriage was constantly breaking down, the elements raged, the horses and mules alternately went into a frenzy, and Biondetta claimed that Alvar wanted to destroy them both. Not far from Extremadura, the young man caught the eye of Bert, the sister of his nurse. This honest villager told him that Dona Mencia was near death, for she could not bear the news of the terrible behavior of her son. Despite the protests of Biondetta, Alvar ordered the drive to Maravillas, but then the axle burst again at the carriage. Fortunately, there was a farm nearby that belonged to the Duke of Medina Sidonia. Tenant Marko warmly welcomed unexpected guests, inviting them to take part in the wedding feast. Alvar entered into a conversation with two gypsies who promised to tell him a lot of interesting things, but Biondetta did everything to prevent this conversation. At night, the inevitable happened - the young man, moved by the tears of his beloved, did not manage to free himself from his sweet embrace. The next morning, happy Biondetta asked not to call her anymore a name that does not fit the devil - henceforth, Beelzebub awaits declarations of love. Shocked Alvar showed no resistance, and the enemy of the human race took possession of him again, and then appeared before him in his original form - instead of a pretty face on his pillow, the head of a disgusting camel appeared. The monster with vile laughter stuck out an infinitely long tongue and in a terrible voice asked in Italian: "What do you want?" Alvar closed his eyes and threw himself face down on the floor. When he woke up, the bright sun shone. Farmer Marko told him that Biondetta had already left, generously paying for both of them.
Alvar got into the carriage. He was so confused that he could hardly speak. In the castle he was joyfully met by his mother - safe and sound. The unfortunate young man fell at her feet and in a fit of remorse told about everything that happened to him. After listening to him in surprise, his mother said that Berta had already been bedridden for a serious illness. Dona Mencia herself did not even think of sending him money in excess of the stipulated content, and the good equestrian Pimientos died eight months ago. Finally, the Duke of Medina Sidonia has no possessions in those places where Alvar visited. Undoubtedly, the young man was the victim of deceiving visions that enslaved his mind. The priest immediately called up confirmed that Alvar had avoided the greatest danger that a person could be exposed to. But there is no need to go to the monastery, for the enemy has retreated. Of course, he will try to revive the beautiful vision again - a legal marriage should be an obstacle to this. If the chosen one will possess heavenly charm and talents, Alvar will never feel the temptation to take her for the devil.
