Your money's no good here.

Plot Description
The Baroness Ishal is a well liked woman, in general. Granted, most of the respect she's earned has been begrudgingly given to her after she's 'helped' people learn a 'lesson'. Even though she was born into money as royalty always is, her grandmother was privy to a spell that had been passed down through their family as an heirloom. They kept it close at hand should any of their offspring reveal a tendency towards selfishness or was otherwise morally bankrupt and used their position and money unwisely.

The spell was a curse, and a minor one at that, but it was effective. Called Glitterblight, the curse would make people that were the recipient of any form monetary compensation acquire a rather quick and severe disposition against the cursed person, within moments feeling as if they'd been swindled in the exchange somehow, and that the cursed person had only the worst possible intentions for the results of the exchange.

Luckily the curse has quite a few intelligent options to provide as far as breaking it. When cast, it can be declared for just a specific time frame, to let the cursed person see what it's like to walk in the shoes of the poor for a couple weeks until they learn the lesson 'Money isn't everything'.

The second version is far more potent, and has been used in the past to turn what was normally a thriving merchant business into ruins. Usually, that was for everyone's benefit, but it still allowed the royal family passing this spell down to maneuver itself to a place of some importance among the other royal families.

All this is well and good for the history books, but the real problem here is the current inheritor to this curse. While she has been subjected to this curse herself and knows it's affects firsthand, in addition to learning her lesson and respecting more than just the gold that fuels the economic world, she was inspired by the lesson she learned and decided to 'teach' the morally bankrupt of the world the same lesson so that they may become enlightened.

Not everyone likes being enlightened.

Baroness Ishal travels with a large caravan like entourage, touring the lands to dine with prominent people and decide if they should learn their lesson or not. She recognizes a certain degree of respect for money must exist, so many people are able to keep up appearances for the Baroness while she keeps up her appearance to be visiting on a social call, rather than her own personal jihad against greed.

When word reaches her ears that the PCs have been known to buy their way out of a jam, she arranges to have her entourage meet with them to discuss their activities and how interaction between her house and the PCs could benefit of them both.

Unless they really genuinely can go through the evening and show charity is in their souls, through the informants disguised as beggars, urchins or just good farmer folk in need of a hand in replacing a busted wagon wheel, the PCs are indeed getting cursed, all of them, with the 'lesson' curse.

But then the Baroness is struck by an attack and lies now, deathly ill, having been targeted by one of the people she 'enlightened' and yet ruined. Poisoned, but not by anything pure, she is feverishly ill. For once, the PCs are not the suspects in such a crime, since the baroness' entourage has been focused on them, their innocence is known. Being close to the Baroness however, makes them the most reliable source of help to finding her cure.

While the Baroness lies with no way to see if the PCs learn their own lesson, they are left to either convince the spell (the DM) they have good intentions, or find the poisoner and acquire the cure all without spending any money.

The poisoner is more difficult to find than you might think. Having 'learned his lesson', he knows how to live poor, and that gives him the ability to blend in perfectly with the unwashed masses. Some common, but hard to conceal physical deformity sets him out, like a club foot or a wine stain birthmark covering his left hand, but who hasn't seen a commoner with dirty hands? It will be difficult, but not outright impossible to find him.

The good news is that the poisoner wasn't able to get a hold of the best poison, in fact, it was worse than the bargain-rate poison he had hoped for. The Baroness will remain struck with a fever for quite some time, it will take weeks of malnutrition before she actually passes away, since she is still able to take some liquid, even thin broth while laying feverish. The bad news of that would be weeks of tracking while cursed.

The PCs are not without their loopholes though. They can't use money, not without being persecuted through the curse, but they can still participate in economic transactions for items of value, rather than items representing value. They can still trade a cow for a sword, give up a potion in exchange for a nights stay, so forth. They can also still work for a living. But unless they're trading gems with a jeweler or other person who crafts with gems, and getting items in return rather than coin backed by a government, they can't even use jewels.

Once they've suffered sufficiently, they are able to catch up with the poisoner and get the cure.