prokopetz:

More inadvisable premises for low-level Dungeons & Dragons adventures:

• The party has been hired by a local inkeeper to clear a infestation of
  giant rats out of their basement. Upon investigation, however, the rats demand parley, and produce documents which – they allege – establish that they themselves are the legal owners of the inn. As far as any player character in possession of appropriate skills is able to determine, the documents are genuine.

• A group of townsfolk ask the party to liberate them from their terrible
  wizard-king. When confronted in his private sanctum, the
  “wizard” breaks down and confesses that he’s a failed apprentice who’s
  been running a Wizard of Oz scam with the aid of a few minor
  cantrips. He begs the party not to expose him, claiming that the
  countryside is home to a band of vicious marauders who’ve only refrained from ravaging the town because they believe he’s the real deal.

• The party receives the opportunity to enter themselves into a region-wide martial tournament whose returning champion has promised to bestow her magnificent enchanted blade on anyone who can best her in single combat. The usual tournament shenanigans are afoot, of course, but the true intrigue is that the champion is really just a luckless merchant who’s been possessed by the malicious intelligence of her sword – and it’s looking to trade up to a better host!
• A village is afflicted by an apparent curse that’s transforming plants, animals, and eventually people into grotesque monsters. The victims typically aren’t dangerous or hostile – just terribly confused. It’s eventually discovered that a local hedge witch has been improperly disposing of failed personal enhancement potions, and the resulting trasmutative effluvium has tainted the village well.
• An evil sorcerer has crafted an army of unstoppable behemoths of iron and bone to rampage through the countryside spreading terror and devastation as a prelude to eventual conquest. However, the sorcerer in question is a member of a very, very small race, so the behemoths are only about three feet tall.