It's set in L.A. and I think it's post BTVS. Angel has lost his soul and there is a demon who's pretty much shut down the city. The demon is large and fire red/black. It basically looks like a red hot charcoal briquette shaped like a minotaur.
Xander takes some slayers into the city. Stuff happens. They take refuge in an old warehouse and happen upon an injured Spike.
The details I remember: sleeping bags, Xander holding Spike's hand during sleep to stop Spike from having nightmares, Xander rigging up a shower in the restrooms, Spike being very weak.
I know it's not much to go on, but I really hope someone can help, 'cause I'm jonesing BAD!