Mightily Oats has not picked a good time to be priest. He thought he'd come to Lancre for a simple ceremony. Now he's caught up in a war between vampires and witches. There's Young Agnes, who is really in two minds about everything. Magrat, who is trying to combine witchcraft and nappies, Nanny Ogg ... and Granny Weatherwax, who is big trouble. And the vampires are intelligent. They've got style and fancy waistcoats. They're out…