The Funhouse by Dean R Koontz

This early Koontz story was written under one of his pseudonym Owen West and is a novelisation of a screenplay, which explains much of its lack of development.  The characters are very two dimensional and sympathy is difficult to find for them.  Amy Harper is a confused teenager, the daugther of a fanatical catholic alcoholic, Amy is torn between feeling that she is wicked and that her mother is the one that is not normal.  Her brother Joey is terrified by her mother's night time visits to his bedside when she belives him asleep and whispers that she is afraid that he is truly evil beneath the skin.  Their father is largely absent and ineffectual.  But Ellen hides a secret.  She is also the daughter of a fanatical catholic mother and when she was a teenager ran away to the fair to live a carny life.  She bore her handsome husband a child but he hid a terrible past of child neglect, self blame for the death of his mother and siblings in a fire, and turn to Satanism.  The child is a terrifying freak and Ellen kills the child, is beaten and left with the promise that her husband will find her and kill her children.  Obviously the fair finally comes to town and Amy and Joey end up in the Funhouse where their mother's secret almost kills them, but they escape.  Very black and white, even down to Amy's best friend who is heavily promiscous and she, her randy date and Amy's equally frisky partner, who have just agreed to a threesome, die in true Scream style.  This did, however, lay the groundwork for Twilight Eyes which is a much better version, although women still idealised in that too