This story is swiped from something that happened to a friend of my mother’s, though I’ve changed it quite a bit.
Abigail is a woman in her late sixties. She has two children, Betty and Bob: the girl was average in most respects and the boy was severely autistic. Abigail spent heroic amounts of time and energy to turn Bob into one of those really high-functioning autistic types, and it worked: Bob is now a highly-paid and -valued member of some IT firm. He’s still socially clueless, though actually rather handsome. Abigail spent so much time on Bob that she neglected Betty, who turned into a lesbian separatist or someone similarly unlikely to ever breed. What Abigail wants is a grandchild, because she knows autism isn’t heritable, really, and because she wants a “normal” baby to love and hug. Bob likes sex but couldn’t care less about relationships, or rather actively avoids them.
So Abigail, who lives a few hours from Atlanta, decides to find Bob a mate. She hits upon this dreamy girl who works some really low-level job, but who has childbearing hips. She brings the girl, Carol, to Atlanta and introduces her to Bob. Carol figures it’s a good trade: she won’t have to work, Bob rarely bothers her because he’s focused on his work, and she can do her art, which is something kind of crappy that involves layers: marbling paper or something impractical like that.
It works great, but Abigail keeps bugging them about kids. Carol is an utter narcissist, so she wants a kid because it will be the planet that orbits herself as the sun. Bob couldn’t care less, but wants to make his mom happy. So they try. And try. And try. Bob discovers he quite likes sex, and wants to do it more. Carol is lazy and narcissistic, so she mostly lies there. It takes her forever to get pregnant, and then she miscarries. This happens again, and again, and again. Both of them are ready to throw in the towel but for Abigail, who bugs them to do in vitro, which doesn’t work, either. Finally, donor eggs and Bob’s sperm find place on the rocky surface of Carol’s womb. Carol is beyond caring at this point: it’s all about her, and this other woman’s eggs don’t make her happy. But she knows very well where her meal ticket lies, and Carol doesn’t want to have to work.
Once the baby, Edgar, is born, Carol completely refuses to nurture him. “All my babies are dead,” is her tagline. But Bob turns out to just love the shit out of him: this is like an emotional breakthrough for him. Yet his work schedule prevents him from doing all the parenting, so since his wife is useless, he hires a nanny, Doris, to do the heavy lifting while Carol stays upstairs marbling paper. Doris figures out how lazy Carol is, Carol (who’s not stupid at all) doesn’t like it, and fires her. Before Bob can find another nanny, in steps Abigail, the hypercompetent martyr, who’s going to take care of Edgar. Since Abigail was the one who found Carol in the first place, she’s kind of blind to Carol’s manifest flaws. What she figures is that Carol has postpartum depression; Abigail busies herself trying to get Carol to get treatment.
Meanwhile, now that Bob has leveled up in emotions, he finally clocks that his coworker Fiona has the hots for him. Since Carol has refused to even touch his penis since the third or fourth miscarriage, Bob is thrilled with this turn of events. They start an affair.
Carol is being driven mad by Abigail, who just will not leave her the fuck alone, constantly bringing little Edgar by when Carol wants nothing to do with him. Finally, in a fit of desperation–Carol’s main motivation is that she doesn’t want to leave her comfortable little nest–she goes with Bob to some work function, where she meets Fiona. Since Bob is guileless, Carol clocks Fiona as Bob’s girlfriend right away, while Fiona, who’s extra sensitive to nuance (she has to be, to date Bob) quickly figures out what Bob can’t and Abigail won’t see, which is that Carol is a worthless mooch. She opens a discussion with Bob/Abigail about what if Bob divorced Carol, kept Edgar (who isn’t biologically Carol’s) and let Fiona move in?
Carol figures this out, or overhears it, and realizes she’s threatened. So she cooks up a plan: remember, she has layers. She murders Abigail in such a way as to frame Fiona for it: she plants evidence to indicate that Fiona knows she can never have Bob fully to herself with his mother around. The twist is that there’s a double-frame, in that it appears initially that Fiona was trying to frame Carol for the crime.