In this very short, short story the climax takes up a minimal amount of space. Events move quickly to the climax. The niece tells her "[r]omance at short notice." Mrs. Sappleton comes in and listens half-attentively to Framton Nuttel drone on about his diagnosis and treatment. Then her attention is focused fully on the vague figures approaching the open window (the style of window that runs from ceiling to floor and is raised wide open to serve more as an open door than an open window). The climax occurs as Framton looks at Vera, who sits "with a dazed horror in her eyes," then is overcome with "a chill shock of nameless fear" as he looks out the open window to see figures who had, according to Vera, disappeared three years ago. The falling action begins as Framton runs in terror from the house.
In a chill shock of nameless fear Framton swung round in his seat and looked in the same direction.
In the deepening twilight three figures were walking across the lawn towards the window, they all carried guns under their arms, and one of them was additionally burdened with a white coat hung over his shoulders. A tired brown spaniel kept close at their heels. Noiselessly they neared the house, and then a hoarse young voice chanted out of the dusk: "I said, Bertie, why do you bound?"
Framton grabbed wildly at his stick and hat ... in his headlong retreat.
Suspense and foreshadowing are built by the same devices. Mrs. Sappleton is the key to both. Her divided attention, half listening to Framton and half searching the landscape outside the window, build suspense because we dread the reality of the niece's story coming to pass. This same attitude and divided attention serve as foreshadowing of the truth since we have a clue to what the truth might truely be and, after the resolution, we have a signpost to look back at to confirm what we discover at the end.
[Framton] was conscious that his hostess was giving him only a fragment of her attention, and her eyes were constantly straying past him to the open window and the lawn beyond. [...]
Then she suddenly brightened into alert attention - but not to what Framton was saying.
"Here they are at last!" she cried. "Just in time for tea, and don't they look as if they were muddy up to the eyes!"
The climax is the point of highest tension in the story, usually the point at which the ending becomes clear. It will occur toward the end of the novel. Foreshadowing is a hint or clue as to somethng that will happen later on in the story.