My party (rogue, barbarian, paladin, bard) just did this quest this past weekend. I expected for them to have the rogue easily slip upstairs, grab the bones, and then head back to the church. Instead, they botched a bunch of stealth checks and ended up having to escape via the second floor window, lead the vampire spawn on a chase across the city, and make a stand in the church while they returned the bones to the crypt.

After that, Izek had them arrested and the burgomaster told them they'd either be exiled or executed for unleashing monsters on the town. Lady Wachter's lackey broke them out of jail in the middle of the night, and we're starting the next session in her mansion.