THE OBLONG BOX (1844)

The unnamed narrator of this story is sort of an anti-Dupin. On a sea-voyage, he notices some odd behavior in the party of a well-to-do man, who happens to have a large "oblong box" in his luggage. The narrator attempts to suss things out and comes to completely wrong conclusions. The truth only comes out because the ship takes on water and sinks, which causes the man with the oblong box to reveal its entirely mundane contents.

The title was the only thing the 1969 movie had in common with Poe.