The novella is set in 19th-century Styria, which is located in Austria. It is narrated by a young woman named Laura, who tells her story to Doctor Hesselius, whose papers are being organized by an aide.Laura lives with her father (a widower) in a castle deep in the forest of Styria. It is an isolated but beautiful and serene place. Besides the servants, the only inhabitants of the castle are Madame Perrodon, a governess, and Mademoiselle De Lafontaine, a finishing governess.Laura narrates that her first distinct memory of her life is from when she was six years old. She awoke in the middle of the night without any nurse or other attendant. She was not afraid until she saw a lovely young woman at the foot of her bed. The woman came and laid down with her and they fell asleep. Laura then awoke to the sensation of two piercing needles below her throat, and the woman fled to under her bed. When her nurse and others came, they felt the spot next to the child and realized it was warm, but Laura's father dismissed it all as a bad dream. Laura remained afraid of the night for a long time afterward.At present, Laura and her father are expecting General Spielsdorf, a neighbor, and his niece, a young woman Laura's age with whom she is excited to spend time since she is often lonely. A letter arrives bearing bad news, though-General Spielsdorf says his niece is dead, and rambles incoherently about seeking vengeance. Laura is very disappointed.That same day though, Laura and her father espy a carriage coming toward them at breakneck speed, and it crashes near their castle. Everyone seems to be okay, including an older, elegant lady and her young daughter, who is unconscious but alive. The old woman says she has urgent business and wonders if she can leave her daughter here. Laura is thrilled because the young woman is beautiful and charming, and she has been cruelly deprived of the General's niece. Laura's father agrees. The old woman pulls him aside and says that her daughter, Carmilla, will say nothing of herself and where she is from; it is a matter of importance.Carmilla is brought inside and a doctor visits and proclaims that she is going to be fine. When Laura meets her for the first time, she is struck anew by Carmilla's loveliness as well as by the fact that Carmilla was the young woman from her encounter when she was six. Carmilla tells her quickly that she too had a similar encounter when she was a young girl, and in it Laura was the older girl; she concludes that they were meant to be friends and Laura agrees. Carmilla is open, warm, and effusive with Laura, who wonders at this level of confidence. She feels a tiny degree of repulsion but the attraction overwhelms her.The two become fast friends and are enraptured with each other. Carmilla has a few odd habits, such as locking her door from the inside at night, not coming down until one in the afternoon, and displaying an intense lassitude. She also has moments when she is utterly consumed by a passion for Laura and kisses, grasps, and tells her they will be one. Laura finds this odd but cannot help but return Carmilla's affection. Laura wishes Carmilla would tell her more about where she came from, but Carmilla firmly but kindly rebuffs her questioning. As for religion, Laura learns Carmilla was baptized but she never takes prayers with them, and one day expresses disdain for a retinue of peasants singing a hymn. She does seem superstitious though, purchasing a charm from a traveling hunchback against the "oupire" (vampire) said to be in the region and urging Laura to do so as well.Laura and her father come to realize that Carmilla is probably descended from the same line as Laura's mother-the Karnsteins, an ancient and noble family in the region whose name and title have long since died out. This is brought to light when a portrait of Mircalla, Countess of Karnstein, is brought back to the castle after having been away for cleaning...