As a young girl, Lucy Snowe visits her godmother, Mrs. Bretton, about twice each year. It is a warm, active household, and Lucy loves Mrs. Bretton. During one of Lucy’s visits, young Polly Home, whose widowed father is leaving England for the Continent, comes to stay with the Brettons. Polly is mature and worldly for her years, and she develops a tender, almost maternal, fondness for Mrs. Bretton’s son, Graham. Because Lucy shares a room with the young visitor, she becomes the recipient of her confidences. Polly’s father had originally intended to send his daughter to Mrs. Bretton’s home for an extended stay, but he becomes lonely for her and returns to take his daughter back to Europe with him. Lucy’s visits with the Brettons come to an end when they lose their property and move away. After that, Lucy loses track of her godmother.

As a grown woman, Lucy earns her living by acting as a companion to elderly women. Tiring of her humdrum existence, she travels to France. There an unusual chain of circumstances leads her to the city of Villette and to a school run by Madame Beck and her kinsman, Monsieur Paul Emanuel. Owing to Lucy’s calm disposition, ready wit, firm character, and cultivated intellect, she soon receives an appointment as instructor of English at the school.

Attending the school is Ginevra Fanshawe, a pretty but flighty and selfish girl whose relationship with Lucy takes the form of a scornful friendship. Madame Beck is a clever schoolmistress. She conducts her school, which has both day students and boarders, through a system of spying that includes occasional furtive searches among the personal possessions of others and also a constant stealthy watching from her window. Despite Madame Beck’s behavior, Lucy feels a firm respect for her. Her system is steady and unflagging. Monsieur Paul is a voluble and brilliant instructor. He always seems to be at Lucy’s elbow admonishing her, tantalizing her intellect, attempting to lead her. Often, Lucy attributes the peculiar notions of the pair to their Catholicism, which Lucy abhors. Dr. John, a handsome, generous young practitioner who attends the school’s students, is a general favorite at the institution. Although she does not betray her knowledge, Lucy recognizes him as the John Graham Bretton, whom she had known as a child.

In her characteristically scornful and triumphant manner, Ginevra Fanshawe confides to Lucy that she has a pair of ardent suitors: Isidore, who, according to Ginevra, is madly in love with her, and Colonel de Hamal, whom Ginevra herself prefers. One night in the garden, Lucy finds a letter intended for someone at the school. Dr. John appears in time to assist Lucy in disposing of the missive before the spying Madame Beck can interfere. The young doctor apparently knows the person for whom the letter is intended. Some time later, Lucy learns that Ginevra’s Isidore is Dr. John himself, and that the nocturnal letter had been sent by de Hamal; Dr. John had been trying to protect his beloved. Dr. John confesses that he hopes to marry the schoolgirl.

Alone at the school’s dormitory during a vacation, Lucy is overcome by depression. She has been haunted in the past by the apparition of a nun, and the reappearance of this specter so exacerbates the already turbulent emotions of the young teacher that she flees into the streets of the town. There she wanders, driven to despair by her inner conflicts, until she comes to a Catholic church. Under a strange compulsion, she is led to make a confession to the priest, but she later regrets her action. While trying to find her way back to the school, she faints. Upon regaining consciousness, she finds herself in a room with familiar furnishings. She is in a Villette chateau occupied by her godmother, Mrs. Bretton, and Graham Bretton—the man known at the school as Dr. John. Graham, who is giving Lucy medical attention, for the first time recognizes her as the young girl who had so often stayed at his home in England.

Lucy becomes a frequent visitor in the Bretton home. Before long, she realizes that she is in love with Dr. John. The warm friendship between the two young people is the subject of constant raillery by the sarcastic Monsieur Paul. While at a concert one evening with Dr. John and Mrs. Bretton, Lucy notices Ginevra in the audience. The schoolgirl begins to mimic Mrs. Bretton, and although the older woman is unaware of her actions, Dr. John is not. Quite suddenly, seeing how irreverently Ginevra can behave toward a woman as good as his mother, he realizes how weak and selfish the girl is, and his infatuation with her ends in disgust.

At another concert he attends with Lucy, Dr. John rescues a young girl named Paulina Bassompierre from a rough crowd. Upon bringing her home, he discovers that she is in reality Polly Home. Repeated meetings between Polly, who is now called Paulina, and Dr. John foster the doctor’s love for the girl who has loved him since childhood. Lucy, closing her eyes and ears to this grief, believes that Dr. John is lost to her. Fortunately, a new phase of life begins for her at the school. Madame Beck gives her greater freedom in her work, and Monsieur Paul shows a sincere interest in her mind and heart. The only flaw in Lucy’s tranquillity is the reappearance of the apparition of the nun.

One day, Madame Beck sends Lucy on an errand to the home of Madame Walravens. There Lucy is told a touching story about Monsieur Paul. In his youth, he loved a girl, Justine Marie, but her cruel relatives refused his suit and Justine subsequently died. Filled with remorse, Monsieur Paul undertook to care for Justine Marie’s relatives. There survive old Madame Walravens and a priest, Father Silas, the same man to whom Lucy had confessed. The priest had been Monsieur Paul’s tutor, and he is anxious to keep his former pupil from succumbing to the influence of Lucy, a heretic. Lucy’s affection for Monsieur Paul grows, but her hopes are suddenly dashed when the truculent professor announces that he is leaving France for the West Indies. Madame Beck, always present when Monsieur Paul and Lucy meet, keeps the distraught young woman from talking to him. Ginevra Fanshawe has meanwhile eloped with de Hamal. A letter from the runaway girl explains Lucy’s ghostly nun—de Hamal had thus attired himself when making nocturnal visits to Ginevra.

On the eve of his sailing, Monsieur Paul arranges a meeting with Lucy to explain his sudden forced departure and recent silence. Surrounded by his possessive relatives, he has occupied his time with secret arrangements to make Lucy mistress of the school. To avoid the temptation of telling Lucy about his plans before they were consummated, he has remained apart from her. He promises that upon his return, in three years, he will rid himself of all his encumbrances so that he will be free to marry her.