An unamed narrator marries Morella, a woman who delves into mysticism. As a result of her experimentations, her soul can never die, but her physical form continues to deteriorate. She spends her time in bed and teaches her husband the black arts. Realizing her curse, her husband, the narrator, becomes frightened and wishes for his wife's death and eternal peace. She dies in childbirth but her soul passes into the new baby.

As the daughter gets older, the narrator notices she bears an uncanny resemblance to her mother, but he refuses to give the child a name. By her 10th birthday, the resemblance to Morella is frightening. Her father decides to have her baptized to release any evil from her, but this event brings the mother's soul back into her daughter. At the ceremony, the priest asks the daughter's name, to which the narrator replies, "Morella". Immediately, the daughter replies, "I am here!" and dies. The narrator himself bears her body to the tomb and finds no trace of the first Morella where he lays the second.