After a five-year absence and learning of her ex-husbands death, Bette moves back to town to live with her son and brother-in-law. Bette and the Uncle get it on together and decide that they want to get married. A love triangle grows between Bette, her son & the uncle and the three of them live 'together' as a threesome happily ever after.
After his father is killed at work, young Billy and his mother get closer, in this first chapter, there's very little sex, but towards the end, they meet up with some people my regular readers may recognize!
It's a male bisexual's dream -- hooking up with an MF couple and having explosive sex with both of them. Oddly enough, though, the sex isn't the best part of it. It's the sense of belonging.