In a post from a little while ago about authors unexpectedly having recycled ideas in their novels from other sources, mention was made of the Norwegian writer Sven Elvestad’s novel Jernvognen (1909), published under the pseudonym Stein Riverton, the solution of which was…heavily borrowed for a famous novel of detection in the 1920s (and, in fact, another in the 1960s…hint hint…though no-one thought to mention that). The novel in question is rather explicitly mentioned in the comments, so, y’know, beware spoilers.