Most of the other reviews on this site seem to relate to a more modern Penguin edition, which combines "The Turn of the Screw" with another novella, "The Aspern Papers", but I have the older edition in which it is combined with two short stories, "The Pupil" and "The Third Person". Those stories appear to have been selected because of their thematic links with "The Turn of the Screw". "The Third Person" is another ghost story, although in this case a comic one in which two spinster cousins who inherit an old house discover that it is haunted by the spirit of an ancestor who was hanged for smuggling. (The house may be based upon Henry James's own home, Lamb House in Rye).
"The Pupil" is not a tale of the supernatural, but was included because it has certain similarities with "The Turn of the Screw", including a similar ending. It is the story of Pemberton, a young Englishman who is appointed tutor to the son of an American family. The boy's parents are Americans of a type familiar in James's fiction; they are fascinated by European culture, and even more by European high society, and spend all their time travelling around Europe in a vain attempt to break into that society. Although the family are financially embarrassed, and rarely have enough money to pay Pemberton his wages, he remains with them, largely because of his fondness for his teenage pupil. (James, himself a repressed homosexual, may be hinting at a sexual attraction between them, although the moral code of the 1890s meant that he could never do more than hint about such matters).
"The Turn of the Screw" is the longest and by far the best-known of the three stories. It is ostensibly at least, a ghost story. Like a number of other nineteenth-century authors writing about the supernatural, James uses a device known by the German title "Rahmentechnik", or "framework technique"; a well-known German example is Theodor Storm's novella "Der Schimmelreiter" ("The Rider on the White Horse"), written ten years before James's story. The purpose of the device is to distance the author from his narrative by making it seem like something he once heard about, or something that happened to an acquaintance, rather than something which happened to him in person. James, in fact, here uses a double framework; the narrator listens to his friend Douglas reading a manuscript written by an unnamed female acquaintance, who is now dead.
In her youth this woman worked as a governess for a wealthy gentleman who had become responsible for his orphaned nephew and niece. She travels to her employer's country home in Essex whereas he remains in London; he takes little interest in the children and in fact explicitly warns her not to bother him with any communications. Despite the eccentricity of her employer, the young woman is initially delighted by her work and adores her two young charges, Miles and Flora. Two things, however, disturb her happiness. The first is the mystery surrounding Miles who has been expelled from his boarding school for reasons which are never made clear. The second is that the governess begins to see the figures of a man and woman whom she believes to be the ghosts of her predecessor, Miss Jessel and of Peter Quint, one of the servants, both of whom died not long before her arrival at the house.
Although "The Turn of the Screw" is a ghost story, it is very different to the sort of ghost stories written by Henry James's younger contemporary and unrelated namesake M.R. James. Although M.R. never explicitly stated whether he believed in ghosts himself, his stories are based on the assumption that the supernatural is real and that ghosts do exist; the sceptical reader needs to suspend his or her scepticism in order to enter into his fictional world. With "The Turn of the Screw" no such suspension is necessary. The story is famously ambiguous as to whether the supposed ghosts are real or a mere figment of the governess's overwrought imagination; this is a point over which critics have argued for decades. (Edmund Wilson is said to have changed his mind twice). The use of first-person narration and the "framework technique" increases this sense of ambiguity; even if we accept the original narrator (who is not necessarily to be identified with James himself) as infallible, he is not speaking of his own personal experiences but only of something which allegedly happened to the friend of a friend. M.R. James occasionally used a "frame" in his stories- an example is "The Mezzotint", coincidentally also set in Essex- but does not distance himself from his narratives in the same way.
Although its supernatural element may be imaginary, the story nevertheless falls within the "Gothic" tradition of English horror writing. The central character's profession calls to mind Charlotte Bronte's "Jane Eyre", another Gothic tale which features the most famous governess in English literature. Certainly, James's young governess herself is in no doubt as to the horrid reality of the "ghosts"; she is terrified of them, not on her own account but on account of the children to whom she believes the ghosts pose some terrible danger, a danger that may lie as much in their power to corrupt the children's innocence as in their power to do them physical harm. The governess discovers that her predecessor and Quint were lovers- something which would have been far more shocking in late Victorian England than it would be today, and there is a hint that she fears that they may also have molested the children sexually. Of course, if one takes the view that the ghosts are purely imaginary, it may be that the real danger to the children comes from their deluded and hysterical governess. Whatever view one takes of the ghosts, however, "The Turn of the Screw" is a skilfully written exercise in creating an atmosphere of psychological terror.