From publisher blurb:
Mini-Dungeon adventure for four to five characters of level 3
With its wide hull and shallow draft, the Silver Swan easily sails the great lake and its connecting rivers, ferrying passengers and cargo throughout the region. Captain Diran Coralini and her crew are known for offering swift and reliable travel, even when other ships are becalmed. Rumored to be able to call upon the winds, Coralini's secret is a magical incense burner she uses to summon an air elemental to fill her sails if the need arises.
Kurzen, a cultist of Pazuzu, learned of the magic censer from the ramblings of a drunken sailor. Seeking to turn the elemental to the service of the demon lord of foul winds, Kurzen has concocted a plan to steal the censer from under the captain’s nose. However, the cultist did not count on adventurers also being on board.