From the publishers blurb:
Adventuring in the Misfortune Lands is a series of adventures designed for any OSR game or ruleset. This is Abyssea Cave, the first adventure in the series, tailored for low-level adventurers ranging from levels 1 to 3.
The Abyssea Cave is known to be an isolated cavern near the sea, seemingly devoid of activity. Its remote location, far from major cities, means it rarely sees visitors. However, significant events transpired here before the adventure begins: a boat en route to these lands was invaded by a group of half-man, half-fish monsters known as the “Werish.” During the invasion, they plundered the ship’s treasures and kidnapped two individuals as part of a deal made with a cultist leader. Following these events, the Werish found a secure location to establish their base—the Abyssea Cave.
In the aftermath, rumors began to circulate in the nearest village about the missing boat that typically brought new arrivals to the land. Locals whispered that what was once a cave where herbalists gathered plants was now overrun with monsters.