Spoilers for a short story that is over a hundred years old. Why haven’t you read it yet? It’s free on the internet!
Dagon is one of the first stories H. P. Lovecraft wrote as an adult. It is both typical and atypical of his Horror work. Typical in that its protagonist goes where he shouldn’t and is driven to suicidal madness. Atypical because the protagonist is he really doesn’t deserve his fate, as he doesn’t seek out what he finds.
Quick summary:
It’s World War I and the Germans have captured the main character’s boat. Not wanting to be a prisoner of war he escapes in a life boat. After floating aimlessly for some time an underseas eruption hurls what passes for an island up from the ocean floor. This imprisons his boat, forcing him to explore his environment. In this exploration he not only discovers that there are titanic fish people in the world but also get to see one up close. His escape from the situation leaves him mad, and, believing himself pursued by the fish man, writes his tale down before the fish man comes for him and he’s forced to kill himself.
All of this, is told in the first person from our protagonist’s perspective. There is a very slight chance we can interpret the whole thing as the ravings of a mad man. The ending helps in this regard, as it’s hard to believe that a desperate man would keep writing as a titanic fish person fumbles open his apartment door.
Outside of the ending and the reoccurring problem that Lovecraft thinks his readers are as well read as he is, the story is pretty good. I’ve seen it compared a lot to Call of Cthulhu, but in fairness it’s not trying to lift the same weights Call is going for. It does it’s job. It may not be one of his bests, but it sure isn’t one of his worst. Especially worth considering is how early it is in his career.
Not a favorite, but I reread it now and then.