I'm pretty sure I read this on Sinister Attraction, but I can't be sure...
It's an AU, and Spike and Buffy go into this abandoned house and get trapped inside of it. A "Shining" thing kind of happens, and it controls Spike's demon. Even after the scoobies are able to get them out of the house, Spike is still all feral from being possessed, or something like that. It ends with Xander bulldozing it down.
So...halp plz?