A central part of the backstory in The Rule of Four is the conflict between the humanists of Renaissance Florence and a prominent religious figure. The religious figure felt the flourishing arts of Italy were detracting from people's devotion to God. He then organized the annual burning of these object on Fat Tuesday -- the Bonfire of the Vanities. The author of the mysterious book in The Rule of Four made it his mission to oppose the religious guy. He began gathering precious works of art, books, maps, etc and hiding them away so they wouldn't be destroyed.

You could certainly use this as a basis for a D&D game. The PC's find clues to where the precious items are hidden (the largest of these clues is the book itself) and spend the campaign tracking them down. It's your standard "loot the dungeon" style game.

But what if the PC's worked for the guy who was writing the book? Their job would be to recover and/or acquire all those books and works of art for a mysterious patron. The patron is actually building dungeons and crypts to hide the items in so he can save them from the growing hostility toward those things in the culture. Maybe the mysterious patron has a vision or something about a night of fire, when items will be destroyed. Maybe he's collecting magic items, because he knows of a growing anitpathy towards magic or a cataclysmic event that will destroy magic items that are not protected. At first, the patron is mysterious and unknown to the PC's. They just get hired for jobs -- find this item, escort this caravan, deliver this letter. Then, they get drawn into the plot more and more and find out they are actually helping to MAKE dungeons. Maybe they will try to prevent the cataclysm that is supposed to happen. Maybe they will come into conflcit with the figure(s) that are trying to burn the art. Maybe they will turn on their patron. Lots of things could happen. I just like the idea of PC's helping to make dungeons and hide away treasure.

Does this sound fun?