Horror short story
"A School Story" is the first story in the second collection of ghost stories published by M. R. James, More Ghost Stories.
A School Story Wikipedia
Two men are discussing the folklore of the private schools they attended. One tells of a Latin teacher named Mr. Sampson who kept a Byzantine coin that he would show his students. The narrator's friend gives the teacher a strange message in Latin which translates to "remember the well among the four yews", though he doesn't know why he wrote it. Later another paper shows up translating to "If you don't come to me, I'll come to you", and it visibly worries Sampson. Later at night the narrator's friend sees a man sitting on Sampson's window-sill, but when he returns with the narrator he's gone. Sampson is missing the next day. Years later a body is found - with Sampson's coin - in a well that sits between four trees.