The players in my weekly Savage Worlds game are about to enter a medium sized town where, if they play their cards right, they might get an invite to a dinner party thrown by the local mayor. Seems like the ideal chance for me to throw in a murder mystery, but I'm having a bit of a creative blank at the moment, possibly because I'm also trying to prep for a Necropolis 2350 adventure next week, run our annual work quiz night, and get up to speed with some new stuff on a project.

I'm looking for a fairly straight up Agatha Christie type plot, the players will be some of the guests at the party, 1 NPC will get it in the neck (so no serial killings), and the PCs might end up being the ones investigating. Anybody got any suggestions for adventures I can repurpose? System isn't really an issue as they don't have any game breaking magic at their disposal (one caster, who can detect magic but that's all). Something free or available via someplace like RPGNow would be a bonus. I've also got a big back catalog of Dungeon mags which I am slowly working through but a pointer to specific adventures people have had good experiences with would be much appreciated.

I'm having trouble thinking of one to recommend, but brainstorming one up isn't that hard.  Start at the solution, then work backward.  Give each layer three connections to the one before.  Don't go out of your way to incorporate red herrings:  Players generally confuse themselves.

An Example (that breaks my own advice...):

The keystone:  The mayor's wife is some sort of shapeshifter, caused by an item she owns.  The item holds a malign spirit, which drives her to murder.  She and her husband don't know the item is really responsible.

What clues would this leave behind?
 - Wife's history has periodic outbursts of violent behavior
 - Mayor tries to cover things up
 - The mayor has built a secret place to contain her

This suggests that the scene of the crime needs the following features:
 - signs of violent fight there
 - others can't hear

Crime Scene: Perhaps the mayor has a sound/scry proof room that he uses for private meetings.  One of the town council was murdered there.

Twist:  Mayor had a mistress.  She knows of the wife's condition and wants her gone.  She orchestrated the incident.  The council member advised the mayor to ditch the mistress, so she eliminated two birds with one stone.  What clues would lead to this?
 - potion vial (rage potion?)
 - second set of footprints
 - strange clues leading toward wife (After someone covered things up, why is THIS apparently obvious clue here?")
 - message lured council member/wife to chamber