Stop evil cultists of the Crushing Wave.
The party rescues a member of the Brotherhood of the Cloak in Mulmaster (local mage guild); Drayson Fivestar. Drayson asks them to investigate the murder of his colleague. After some urban investigation, the investigation leads to a former guard tower of the Zhentarim, now occupied by elemental cultists. The tower was submerged in mud, but recently uncovered. The party faces of with the cultists.
(Large page count, but feasible as a one shot after some editing, will probably take two sessions at most)
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