The town of Brightcreek has had a bad couple of years. First, the Mere of Dead Men up north grows dark, deadly, and nigh impassible to traveling merchants. This by itself is bad news, to a town whose main draw is being between Neverwinter and Waterdeep. When the road between them is disrupted by undead and shadows and crazy druids and who knows what else, visitors and merchants are few and far between. Now, just as things started to calm down, when things started to look like they might go back to normal, now suddenly the other side of the coin is in trouble. Waterdeep has gone crazy, with an ominous blood red sky to the south and refugees fleeing to the north rambling of devil armies and planetar and dark elves and other sorts of crazy nonsense.
But the red sky has calmed to the more typical dull grey of the Sword Coast, and the refugees have trickled to a halt. Many of them have even tentatively left to see to the state of their homes. Maybe things will actually just be all right now?
Wait. No. Actually, things will not just be all right now. Instead, a cult that worships a demon steals a girl in the middle of the night, and announces that all who do not bow before their demonic master will suffer unimaginable torment for all eternity, all who oppose them shall suffer even more unimaginable torment, etc. A portal to the Abyss will be opened, and their master will surge forth, there is no hero that could possibly stop their all mighty master, surely.