"The Man That Corrupted Hadleyburg" is a short story by Mark Twain, first published in Harper's Monthly in 1899. It is one of his longer short stories, running around 50 pages in a standard paperback edition. Like much of Twain's work, it combines social commentary with elements of the fantastic, exaggerated or supernatural.
The story introduces us to Hadleyburg, a small town of undisclosed location where all the people are scrupulously honest, at all times, a trait that everyone in the town is raised with to the point where they can't imagine corruption. The town is happy, but apparently they manage to offend a stranger, who launches a plot for revenge against the town. He drops off a bag of gold coins, with a note that someone in the town did him a favor long ago, and says that it is for the person who can remember the line that was said to him along with the favor. The previously pure residents of the town start to think about that gold, and think about what they might have done. Nineteen honest men of the village are given secret letters "reminding" them of what they said, and they all "remember" the event. They then go to a public meeting, where the manipulations of the stranger show that they are all dishonest, where reputations are crushed and the town has a moment of self-realization.
The story ends with the town changing its name and changing its motto from "Lead us not into temptation" to "Lead us into temptation", with the idea being that people have to deal with their dishonest impulses, not be totally insulated from them.
Like much of Twain's writing, the story might not work for everyone. It is more of a fable than a short story: the reader is expected to accept the contrivance of the sack of gold, and the theatrical nature of the townspeople's discussions. Twain can be a bit heavy handed when making a point, and that may or may not be to the reader's taste. But despite the story being very unrealistic in places, its basic message about corruption is realistic. None of the tempted people say "I will lie for money", instead, their own recollections and memories are slowly changed to fit what other people say. No one is ever offered a single choice where they decide with a clear mind or heart whether to be dishonest or corrupt, it is a series of steps where the person adjusts to new standards.
And, as a final note, while it is not directly stated, I wondered whether the man with all the resources and trickery, with the singular intention to corrupt a town of innocent people, was something more than just a normal person with a grudge. While never explicitly stated, apparently many people have identified this figure as Satan.