“The Terror of Blue John Gap” (1910)
Arthur Conan Doyle (writer).
Read in 2017.
A prototypical cryptid adventure. Implausibly, cave bears are theorized to have speciated in an underground cave system, in such a way as to grow tenfold where the expected real-world response would be something like island dwarfism, except for the cold. Foolishly, the protagonist goes spelunking alone, telling nobody, several times, rejecting even the obvious ally (Armitage). Risibly, the mystery is never resolved because locals reseal the cave system, despite great public—and one presumes scientific—attention.