A certain man embarks on a business trip to Mexico. In the train, he finds himself alone in a compartment with someone who turns out to be a dangerous maniac.
Another story being revised for Adolphe de Castro (the previous one being The Last Test). Lovecraft agreed to take it on solely because Castro paid upfront for the revisions. The writer struggled with this text, which held no promise, so for entertainment, he decided to mix horror and a bit of humor for the initiated (something he usually avoided and believed should not be done). Even the grotesque behavior of the madman on the train is spiced up with quotes from a certain German Lovecraft once traveled with to Washington.