Between 1903 and 1908, Lovecraft created many stories and sketches, about which we know nothing today beyond the fact that they existed. Almost all met the same fate: death in the flames at the hands of their creator. Lovecraft saved only two texts – "The Alchemist" (1908) and "The Beast in the Cave."
The sketch of the story was created as early as the spring of 1904, but Lovecraft needed some time in the Providence Public Library to get to know the location where he set the story, i.e., Mammoth Cave in Kentucky (now a national park). The plot can be summarized in one sentence: a tourist gets lost in a vast cave, where he encounters the titular beast.
It is immediately apparent how much Lovecraft had progressed in prose writing since he penned the weak "The Mysterious Ship" three years earlier. The story is mature, with a well-developed psychology of the main character. In the 1930s, the author considered "The Beast in the Cave" to be the first of his works, chronologically, that held any value for him. It is the first story that bears such a clear resemblance to the writer's later works. I particularly note the fact that Lovecraft uses for the first time the phenomenon of the so-called "terminal climax," where the climax coincides with the last sentence of the story. Another striking example of this technique can be found in "Pickman's Model."
The story was not published until 1918, just after Lovecraft returned to writing prose (from 1908 to 1917 he was exclusively engaged in studies and poetry). Lovecraft was convinced to publish it by his friend from the amateur writers' society, W. Paul Cook.