Framton Nuttel is a youngish man who has come down to the country from London for what is described as a "nerve cure." He is a complete stranger to the household where the whole story takes place. He has apparently sent Mrs. Sappleton a letter of introduction from his sister, who stayed in that area with the local vicar four years ago, and Mrs. Sappleton has apparently invited him over for tea. That seems to be the way those things must have been arranged in the days before telephones. Framton could hardly have shown up on the woman's front doorstep with a letter in his hand; she would have had to have some warning he was coming. She would have invited him to tea but not to dinner because she didn't know him well enough.
We know that Framton is very nervous, but we know little else about him. It would appear that he is a member of what used to be a fairly large leisure class in Edwardian England. He can afford to spend as long as he likes in the country, and he is apparently not tied to a job in the city. He can also afford to consult many different doctors. His neurosis is a sort of hobby with him. He belongs to the same social class as the Sappletons, who are able to live in a big house in the country without anyone having any apparent gainful employment. Agatha Christie's mystery novels are full of such character types. If any of the men do any work, it is something vague like "bonds."
Framton is immediately contrasted with his young substitute hostess Vera. In addition to belonging to a different sex and a different generation, she is described as very self-possessed. That is the way she talks and acts--at least up until the time when she pretends to be horrified at the sight of the three hunters who supposedly died three years earlier. Framton is ill at ease being in a strange home on such a slender pretext as having a letter of introduction from a woman Mrs. Sappleton probably hardly even remembers after the passage of four years. In contrast to Framton, his sister, who never appears in the story, sounds like the kind of aggressive woman who would write letters of introduction to people she scarcely knew. Framton would be best described as a neurotic, although that term was not in use in his day. The doctors didn't know what to do with people like him, who suffered from all sorts of imaginary ailments. When Mrs. Sappleton arrives in the living-room, he introduces himself in this way:
"The doctors agree in ordering me complete rest, an absence of mental excitement, and avoidance of anything in the nature of violent physical exercise," announced Framton, who laboured under the tolerably widespread delusion that total strangers and chance acquaintances are hungry for the least detail of one's ailments and infirmities, their cause and cure. "On the matter of diet they are not so much in agreement," he continued.
Framton is a neurotic, a hypochondriac, a Londoner, a youngish leisure-class gentleman, a bachelor, and a stranger to this part of England. He is credulous. He does whatever his sister and his doctors tell him. He is an easy mark for young Vera, who sizes him quite accurately when they first meet.