Whip Hand, by Charles Willeford, Gold Medal Books, 1961. Published under the moniker of W. Franklin Sanders, this early effort by Willeford has never been reprinted but is available now in ebook form. If you want a copy of the first edition, be prepared to shell out a $350 for a collectible copy, a mere 100,000% increase over the original price. This is what we should have been investing our money in in high school.
As lurid as the cover makes the novel seem, this is a serious experiment in multiple narration. You think you're reading flippin' Faulkner when the voice of Junior, comes in. He's just your garden variety psychopath from Oklahoma, doing what he knows best to do when he comes to a strange land like Texas, which is to kill people.
As for the babe with the whip, she's really quite demure and gets all mushy when her big cop boyfriend barges into her mansion with the crook who kidnapped her little sister. Yeah, she can wield that whip, all right, but only because her old man taught her how to use it for self-defense. And she only uses it on Junior, providing the one moment of restraint in the novel.
If you understand the genre, you'll recognize this as a hidden treasure.