"'I'll give you this much,' Mr. Reggie said, and pushed a folded sheet of paper across his desk to Sheridan. 'You might get along with this guy. He calls himself Mr. Wizard, but he's a shitbag just like you. Now get out of here. I'm gonna have you back in here in a week, though, and I'll have your markers on this desk. You either buy them back or I'm going to have my friends tool up on you.'"
--Stephen King, "Popsy"

• The PCs are in debt. A new tax law was retroactively put in place by the government while they were on an expedition and, as prominent adventurers, their wealth is a well-known fact. When they return to town, they find that any permanent residence they once held has been auctioned off along with all the possessions they didn't carry out of town with them. Ironically, when they have no where else to turn to scrounge up the money to pay off their debt, the city's illicit underworld opens up to them, offering to replace their stolen possessions and high-paying jobs if only they'll bend (or break) their morals.
• The PCs' recent exploits have pissed off a major crime boss, and he's not the kind of guy who lets things go. Many people throughout the PC's city owe him a favor, and sometime much more than that, and he's got them all gunning for the PCs. The stupid and inexperienced ones attack immediately, and are most likely laid low by the PCs, but soon experienced assassins are on their trail. The only hope for the PCs is that each assassin wants to be the one the make the kill, and thus have reason to attack each other as well as the PCs. Can they escape the crossfire alive?
• It is a poorly kept secret that those who fail to pay off their debts to Mr. Wizard's Gambling Hall often go missing soon afterward, though few know where they end up, and the general assumption is that they are killed and thrown in the river. This is not that case. The luck ones are drugged and shipped to slave colonies in foreign lands. The unlucky, those who are in some way unfit for grueling manual labor, are subject to Mr. Wizard's eldritch experiments. Those who are foolish enough to dig deeper into the disappearances may hear hushed rumors of amalgamations of cogs, fungi, and flesh strapped to examination tables.