I have no experience with The Dresden Files, so this might not be applicable to your specific situation. I have found that it can work for a variety of games, though.
The "Impossible Mission Team" approach can be a lot of fun if you tailor it to the game world. Short, well-defined missions that are given to the player characters by an organization, powerful benefactor, or unknown entity can provide helpful boundaries. You can keep the PCs from going too far afield by tailoring very specific goals. If you want, you can even create the scenarios in a way that over time reveals a larger plot, but that's certainly not required.
A few months ago we switched our Eclipse Phase campaign over to this format, and it seems to be working well so far. The PCs are Firewall agents. What they do between sessions is immaterial, and the missions are all pretty much of the "We've only got 24 hours to save X" variety. There is a big, scary villain creating much of the havoc behind the scenes, but that may or may not become something the PCs piece together.
t doesn't take much to apply this approach to a wide variety of game worlds:
- The PCs work for the baron, who is having a difficult time keeping the Western Marches under control. When his army detachments run into trouble that they don't have the time or wherewithal to confront, he sends in his special representatives.
- The Sisterhood of the Eightfold Path is fighting a heretical presence within its ranks. The Sisterhood has created a secret organization devoted to rooting out the heretics.
- After the Ragnarok Affair, a mysterious benefactor approached each member of your team, telling them that their superpowers would be put to best use fighting the most dangerous evil villain organization of all. Now the team fights O.G.R.E. across the globe. Every time O.G.R.E. makes a move, you are there to thwart them.
Admittedly this approach constrains the game, but in my experience it can work well as long as everyone understands the difference in approach up front. Getting players to buy into it is essential, so they can keep the game focused on accomplishing the mission.