The party has their bodies switched by an absent minded professor who has simply forgotten to gather the required elements to reverse the spell. While the summary gives the initial reasons for visiting the wizard, the real meat of the adventure is in reversing the spell cast by the wizard. Details below.
The vizier (named Zerradus) of a local lord, Lord Dannor, approaches the characters with an offer of employment. It seems that during a recent dinner party, an uninvited guest, a local absent-minded professor who forgot he didn’t live there, dropped by and had dinner with the other guests. After an evening of lively conversation, he suddenly remembered he did not live there, and promptly left.
The reason the lord wishes to hire the party is that the professor fancied a pendant hanging in the Lord’s entry hall, a sentimentally prized trinket that belonged to ancestors of Lord Dannor. He nabbed it, put it on, and wore it the entire evening. The lord, not wishing to offend the professor, let the ‘guest’ wear the pendant, assuming that he would get it back at the end of the night.
The problem is that the professor is a powerful wizard. While being quite kindly and prototypically absent minded, he is still a very powerful wizard. One does not lightly undertake the retrieval of an object from a wizard, but the Lord REALLY wants the pendant back. He is willing to reward the adventurers handsomely in recognition of their sacrifice if they go and talk to the wizard and convince him to return the pendant. He will "owe them one", and will also pay for their expenses incurred.
The wizard may not remember that it’s NOT his pendant, he might not remember that he even has it. He is not known to be harmful or unpredictable, so diplomacy, rather than brute force, would be the order of the day. The characters are even authorized to simply purchase the item if necessary, and should such an expenditure be necessary, the Lord will gladly reimburse the party.
The wizard, named Vendawan, lives in a tower about a week’s travel west from the Lord’s castle, which is about a weeks’ travel north west of the PC’s home town.
The vizier indicates that the lord is understandably embarrassed, and would prefer his faults to be a matter of discretion rather than public record. This is why he chose to hire outside talent, rather than simply have the local authorities pay Vendawan a visit.
At this point, assuming the party agrees, the characters make their way to Vendawan’s Tower, and, minor extra-adventure interludes aside, reach there in short order.
When the characters arrive, they are ushered into an entryway by a polite old man, with a long flowing beard, wearing a pendant that looks awfully much like the pendant the characters seek.
He ushers them in and says, "good good you’ve arrived! Come on in, take off your cloaks, make yourselves at home, I’ll be right in!" He shows them to a room and runs off into another room. Nothing the party says at this point will seem to even sink in.
A few moments later he comes back in and says, "Edwin sent you, eh? Ok, well come on, follow me, thank you soooo much, you’re being a great help." Note that nobody the party knows and nobody in the party is named Edwin, it’s just a name he throws out. Requests for the pendant go unheeded, as if they weren’t even said. He will ask for introductions.
If the characters ask for the pendant back, the wizard will absently dismiss it until the characters assist him in his task, which is simply to stand in a circle until he tells them he’s done with his little test. No matter what the PCs do, they can’t convince the wizard before they assist him to give back the pendant, and simply taking the pendant would be a TERRIBLE career move (stealing from a powerful wizard tends to end somewhat badly).
When the characters agree to assist, he touches each one on the shoulder, sprinkles some dust on them, and tells them it is very important that they not move. They feel lightheaded, then the world goes dark, and they feel like they are spinning. Then they open their eyes. No one is really quite sure what just happened.
Once the characters recover from their woozy feeling, the wizard will begin asking certain characters questions. "WHAT IS YOUR NAME???" Vendawan is obviously excited. The answers are strange. Each character gives the name of another character! The rest of the characters will see that the characters have rotated their bodies in some manner.
At this point, the mental abilities of each character have switched physical bodies in some seemingly random order(but presumably very well choreographed for the most role playing amusement). All mental abilities travel with the character, including character knowledge, skills and weapons use. The PHYSICAL abilities, however, belong to the body they are in. The ability to wield a sword may be more than slightly impacted if the big and beefy fighter suddenly finds himself in the body of a scrawny wizard. Obviously, this presents a SEVERE challenge to the party, if the situation continues like this. Anyways, back to the description.
Unfortunately, being absent minded like he is, the professor has not yet procured the required elements for the reverse of the spell. The characters are stuck like this until he gets those elements! Oh, but he’ll be happy to return the pendant. He gladly returns the pendant, and absent mindedly wanders off and goes about his day, presumably to the shouts of "hey wait a minute!" coming from every single member of the party.
Vendawan returns, and describes his predicament. The components are only found in the cauldron of a coven, and it requires a hag’s eye as well. The wizard would be more than happy to return them to normal when he’s got those items. He has scryed the location of a nearby coven of hags, and plans to visit there within 6 months at the VERY latest to collect his required components. Just as soon as he gets done the experiments he currently has running… he motions over his shoulder to an almost labyrithian complex of intricate experiments and other wizardly contraptions. It’s obvious this guy isn’t going to get around to it any time soon.
So, what does the party do? Do they hang around, waiting for this guy to get good and ready to fix their little problem, or do they fix it themselves? The wizard would, of course, be happy to oblige the party in telling them where the coven is, and if they’d like to go get the items, Vendawan would be SO pleased, he’s VERY busy at the moment, and he’d like to see if his experiment is a success.
Grumble grumble grumble goes the party, presumably very shortly after that followed by a statement to this effect: "FINE, where is this damn coven?" And presumably off they go.
NOTE: It is critical to remember that the physical attributes of each body are UNCHANGED. Each person is wearing armor appropriate for the body(fighters wearing plate mail, eg). This could interfere with other character abilities, and may require some "modifications". Furthermore, combat will be VERY uneasy for all involved, especially the fighter types, who are used to toe-to-toe slugfests, and they will be WOEFULLY unequipped to deal with that at the moment. Be very clear about that part to avoid unnecessary character death. The party may not have the ability to change their gear at this point, so some people may have to simply "make do". This warning, of course, depends on the system and character limitations.
Possible Adventure Direction
Note: the original version of this post had far more information than the plot needed, so I removed it.
At this point, you can make up any number of necessary and forgotten about spell components that the party must find, and return to Vendawan, and, of course, he’s forgotten about one critical component each time(until you want to end the adventure, with a successful casting).
You can include any number of role playing encounters to play up the whole "new body" experience, and test the conviction of your players to the role playing experience. How well can they role play their character suddenly having to deal with all the hassles of the opposite gender, a different class, and so on.
In this situation, be careful with combat, because the party is likely to be highly combat INEFFECTIVE, more so that you could imagine. Extremely dangerous combat is NOT recommended while their bodies are switched.