The tenor sings of an account he found in the hand of a young and inexperienced Governess who was sent to care for two children in a country house, on the stipulation that she not contact their guardian, a busy uncle in London.

Bly, a country house in England. On her journey to Bly, the young Governess ponders all the uncertainties of her new position. Will the children like her? Will she impress their guardian? When she arrives, she is welcomed by the children and Mrs. Grose, the sympathetic housekeeper. A letter arrives expelling Miles from school for “an injury to his friends.” The Governess decides not to discuss it with him.

She sees a strange man in the tower on the grounds. She describes him to Mrs. Grose, who tells her he must be Peter Quint, the valet to the children’s guardian, who “had his will morning and night” with Miles and with Miss Jessel, the former governess. Miss Jessel went away and died, and Quint died too. The Governess is horrified. She swears to protect the children, and Mrs. Grose promises to stand by her.

In Miles’s Latin lesson he sings a strange song on “Malo,” the word for “bad,” and asks if the Governess likes it. While sitting by the lake with Flora the Governess sees Miss Jessel, but Flora says nothing. Quint and Miss Jessel call to Miles and Flora at night. The Governess intervenes just as they are disappearing, and Miles says to her, “I am bad, aren’t I?”

The great hall. Quint and Miss Jessel converse bitterly, each confessing the desire for “a friend.” The Governess feels lost in a labyrinth. In the churchyard, the children play at being choristers, and the Governess determines to write to the guardian. Miss Jessel appears in the schoolroom, saying she is weary but unable to rest. The Governess writes to the guardian and leaves the letter on the desk. While she is talking with Miles in his bedroom, her candle goes out and Miles claims that it was he who extinguished it. Peter Quint calls to him. At Quint’s urging, Miles steals the letter. Later, while the adults are absorbed in Miles’s piano playing, Flora slips out to the lake to meet Miss Jessel. When the Governess and Mrs. Grose follow her and press her for answers, she denies seeing Miss Jessel (whom Mrs. Grose still cannot see).

Out of concern for the girl, Mrs. Grose takes Flora for the night, and by morning is determined to send her to her uncle. The two women realize that Miles has taken the letter. Mrs. Grose leaves with Flora. Now that they are alone, the Governess asks Miles to tell her what is on his mind. Quint appears and begins calling. The Governess bids Miles name the one who made him steal the letter, and Miles shouts, “Peter Quint, you devil!” He dies in her arms. She sings him a mournful “Malo.”