D&D 5E: Adventure: Fifth Edition Fantasy #33: Sailors on the Starless Sea

Bent on stopping the rash of abductions plaguing their village, the characters discover a horde of vile beastmen inhabiting a nearby ancient keep. Seeking the source of these abominations, the characters uncover an ancient chaos cult and its source: an antediluvian ziggurat set in the center of a vast, underground sea. There, at the font of chaos, the characters witness a wicked rite culminating in the sacrifice of their fellow villagers. Can the heroes muster the courage to interrupt the rite before its conclusion and stave off the rebirth of the legendary chaos lord? Or will they suffer a fate more fearsome than death, as their spirits fuel the infernal might of the reborn chaos lord!