The titular Spook is in fact a young woman who lives in an old house with her mother outside of Dalton, Georgia, and has since she was born. It was the locals who started calling her Spook, and all kinds of urban (or should I say rural) legends arose about her as she is supposedly hideously deformed since birth. Spook (really MaryAnn) and her mother live an isolated existence, with her mother making a living by raiding the dump for things to sell and such, although she was an up and coming artist at one time. Spook only goes out at night and covers her head with a hood.
The story kicks off with Lola Aragon, relocating to the Georgia County as an administrator for the school district. After a spell, she finds out about Spook, who will be 16 soon, and starts some inquiries, finding out that she has never been in school, let alone any social services and such. We follow Spook as she plays with her dogs at night and learn she makes all kinds of 'primitive' art; idiot savant? Who knows. Anyway, Aragon gets a bee in her bonnet about Spook and is determined to do something about her. Vance stretches things pretty lean here-- why would Aragon take such and interest in Spook? She has an entire county of kids to manage after all.
Vance also introduces several other characters, including some local cops (one who quickly becomes romantically involved with Aragon, gag) and some local ne'er-do-wells, teenagers, one of whom has a strange interest in Spook. Also, it seems some bodies keep turning up, including some people Vance introduced as cannon fodder early on. It seems only a matter of time that Spook will be outed to the world, even as her mother, armed with a shotgun and vitriol aim to keep everyone away...
Spook had some moments, and the ending (and the big reveal!) were clever, but overall, pretty unredeeming trashy pulp. This reads like a b-movie screen play and maybe that is what Vance was going for; I can see Roger Corman giving this one a go! This is also more thriller than horror, but so it goes. Better than two stars, but not three, so I will go with 2.5, rounding up for the ending.