The story opens with the elderly priest Romuald recounting the story of his first love, Clarimonde. On the day of his ordination many years ago, he sees a beautiful young woman in the church. He hears a woman's voice promising to love him and to make him happier than he would be in Paradise. Conflicted between 'love at first sight' and his religious beliefs, he finishes the ceremony despite her entreaties. On his way back to the seminary, a page greets him and gives him a card reading: "Clarimonde, at the Palace Concini".Romuald is stationed in a quiet location in the country and feels trapped by his priesthood. He continues his studies but is distracted and plagued by the memory of Clarimonde. Father Sérapion senses something is off with Romuald and tells him about the legend of the infamous Clarimonde the courtesan, who has recently died. Romuald asks Sérapion about the palace, and Sérapion answers that it is the Palace Concini, where Clarimonde lives. He informs Romuald that it is a place of great debauchery. Sérapion warns Romuald that it is not the first time Clarimonde has died. One night, a mysterious looking man on horseback arrives to Romuald's parish, and asks for Romuald to come with him. They ride on horseback to a lavish castle in the country. As Romuald dismounts his horse, he is told that it is too late for the woman and that she's dead. He is led to the woman's chamber to perform the rites, only to discover that the woman is Clarimonde. In his grief, he kisses her, temporarily breathing life into her. She says they will shortly be reunited and Romuald faints as he sees her spirit leave.Romuald believes all that had passed with Clarimonde had been a dream; but a few days later, she appears to him in his room. Clarimonde appears dead, but beautiful, and tells him to prepare for a trip. The two of them travel to Venice and live together. Clarimonde's health wavers and she seems to be dying, but she is restored after she drinks some of Romuald's blood from an accidental finger cut. Romuald realizes that Clarimonde is a vampire, but continues his relationship with her.Father Sérapion pays a concerned visit to Romuald over his affairs with Clarimonde. Sérapion is adamant that Romuald's desires for Clarimonde are born from sin and takes Romuald to her tomb. He reveals her body is miraculously preserved thanks to Romuald's blood. Seeing blood on the corner of her lip, Father Sérapion becomes furious and calls her a demon as he pours holy water on her corpse. She crumbles into dust, but returns to Romuald later that night and admonishes him for his betrayal. She then vanishes forever.Back in the present, Romuald tells his audience that this was the greatest regret of his life and suggests that his listeners never look at a woman lest they meet the same fate, even as he still misses Clarimonde.