From publisher blurb:
In Wake of the Wind Fish, a group of level-4 adventurers visits a water genasi settlement called Zorannia. A mysterious astral fey fish visits the town once a year. The locals call it the Wind Fish and see its annual visits as a source of good fortune and fertility. Something terrible a few days ago when the Wind Fish came for its expected visit. It was sick and weak. A priestess tried to help it but got swallowed in the process to the horror of perplexed bystanders.
An old taboo prevents the genasi from following the Wind Fish to its refuge in the mountain, an ancient temple abandoned generations ago. A drow guide and researcher in town, named Falandir, knows the way up the mountain and is the only person in town willing to investigate the Wind Fish, apart from the adventurers. What no one knows is that an evil creature within the astral fish makes it sick. This quest shall bring the adventurers to the Wind Fish innards to find the malignant parasite.