Carrion Crown was our first campaign, ran by somebody we eventually had a falling-out with. Technically it took place in the middle of a lot of our campaigns, but it does have the feeling of a start of a grand quest to it.
Originally it began with Lillith, Paige, and one other party member that quickly grew ill and died in the town of Harrowstone, where the party had been assembled to honor a fallen professor, and where they first met Kendra Lorrimor, a recurring NPC and the daughter of the Professor, who the PCs had come to pay their respects. They hired two mercinaries, Glen and Alistar, to help them conquer the prison, but the spooks were too powerful for them and they fell to the dangers within. Soon after, Kurono joined them as they set out to remove the ghosts and ghouls that resided in the burnt-out Harrowstone prison. After some crafty finagling by the party, they managed to purge the prison of haunts via cunning and no small amount of luck.
After they finished their task, they finally follow the final wish of professor Lorrimor and deliver his books to the town of Lepidstadt.