In Saki's "The Open Window," what does Vera say happened three years ago?

Vera tells the central character, Frampton Nuttel, that
three years ago a great tragedy occurred in their family. According to Vera, Mrs.
Sappleton's husband and two younger brothers set out for a day of shooting, and did
not return. It was concluded that the three, along with their little spaniel, were
engulfed in the treacherous bog; their bodies were never found. Vera tells Framton that
her aunt, Mrs. Sappleton, speaks frequently about the day the three men and the dog
purportedly met their demise, leaving the window through which they exited that day
open, as if in expectation of their return. As Vera and Framton sit there by the open
window, Vera shudders and tells the visitor that on "quiet evenings like this," she
still gets a "creepy feeling that they will all walk in through the
window."

Mrs. Sappleton comes in at this point, and, as
expected, talks about her husband and brothers, whom she says have gone shooting but
will be home soon, coming through the window as is their habit. Framton, who is in a
delicate mental state, believes, because of what Vera has told him, that the men in
question are dead, and that Mrs. Sappleton is delusional. Disturbed by the ghastly
situation, Framton becomes completely unnerved when Mr. Sappleton, the two other men,
and the spaniel do indeed appear at the window, and he bolts off in terror. Vera, of
course, has misled Framton for her own amusement, and when the family wonders why their
visitor has left so pricipitously, she dissembles further, saying that he was most
likely afraid of the dog.