Which Mark Twain story was published posthumously and features a mysterious stranger?

The Mark Twain story published posthumously that features a mysterious supernatural visitor is The Mysterious Stranger. Twain worked on related versions of the manuscript intermittently from 1897 through 1908, but he never completed a single definitive text during his lifetime.

The 1916 publication appeared several years after Twain’s death and was assembled from his unfinished manuscripts by editors, chiefly Albert Bigelow Paine and Frederick Duneka. Later scholarship showed that the published book combined and altered material from different versions, including The Chronicle of Young Satan and No. 44. This editorial history is why modern editions often distinguish the published novel from Twain’s original manuscripts.

In the story, a figure identified as Satan—or, in another version, No. 44—appears among children and uses supernatural powers to expose human cruelty, superstition, and the apparent meaninglessness of existence. The work is therefore more accurately described as an unfinished novella than a conventional short story. The other choices are genuine Twain works, but none centers on this mysterious supernatural visitor.