Dahl effectively creates tension by setting a nightmarish tale in a seemingly normal, everyday environment. The story takes place in a cosy bed and breakfast in the beautiful, ancient city of Bath. The owner of the guest house seems to be a perfectly respectable, if somewhat eccentric, old lady. Neither we, nor Billy Weaver, have any reason to think there's something unusual about the place.
But gradually we realize that the whole set-up is a facade. There's something quite unreal about the place, something not quite right. There are subtle hints that there's an atmosphere of evil hanging over the house, but really no more than that. The old lady's house is like a museum; although it's only later that we find out exactly what kind of museum it is. The clues are there to help poor, hapless Billy connect the dots, so to speak, but he's been completely taken in by this apparently harmless old granny. Sure, that dachshund sitting by the fire seems eerily quiet, and those names in the guest book ring a bell, but it could all be put down to some good, old-fashioned English eccentricity. In a way, it is; but not quite in the way that either we, or Billy, could ever possibly have imagined.