The story focuses on the protagonist, who decides to go down to a harbor at night despite many warnings by others not to do so.
What happens next is a terrifying encounter with a gruesome Monster that attempts to drag him into the ocean with a tendril and presumably devour him alive.
However the protagonist manages to escape the Monster, which emerged - showing itself as a Lovecraftian monstrosity with vicious, animal-like behavior.
The protagonist is forced to flee as the Monster pursues them, even going as far as dragging itself out of the water and trying to follow the protagonist - awkward on land but reluctant to give up on its prey.
The protagonist continued to flee, not stopping until he reached the safety of his home, the Monster presumably returned to the ocean in search of another victim.