I reccomend "All the King's Men" by Monkey God Enterprises. It's a (humorous) murder mystery that takes place in a fantasy London. It's for about 8-9th level characters, but it doesn't take into mention about what to do about high-level divination spells, etc. I don't know how well it will go with Munckin. However, it has loads of humorous and well-thought out stock NPCs that might prove useful.