Okay, here's the idea. I think the title should be “All Saints' Day”, for part one at least. (It'll be a 2-parter.)
Takes place in October of…oh, say, 2009. There's been more and deadlier ghosts than ever before, and the UK GBs have their hands full, and don't have time to think about where they're coming from!
Pretty soon, help arrives in the form of two men, each one calling himself “The Doctor”, but with different points of view and working methods.
The ghosts are traced to astrophysicist Dr. Hector Goshojin, who is currently studying “a hole in the Universe” that seems to be getting bigger every day. However, he knows nothing about the ghosts, except that they're “only a side effect”.
As they race against time, one of the Doctors realizes that the ghosts have some link to his past. He must find out what before time runs out…
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Time for spoilers, everyone:
The ghosts, leaking through the hole, are the Dark Army, a race of demons who almost succeeded in taking over Gallifrey, but the Doctor had to destroy the planet and defeat them. They've been stewing in their own juices since then, waiting for centuries, and becoming more powerful every day.
Now they've got their sights set on Earth, and they've heard a call leading them towards their ultimate target!