This book is by D T Hughes, not Bettany Hughes. It's the story of Darci Pierce, who in 1987, faked a pregnancy (for about 11 months) then kidnapped a pregnant woman using a non-functioning gun, took her up in the mountains, hit her on the head, strangled her (with a monitor strap found in the woman's purse), then cut her baby out of her with a car key. Darci then attempted to pass the baby off as her own, raising suspicion when she would not allow medical personnel to examine her.
Throughout the book, the author attempts to find some reasoning for Darci's behavior. Darci was adopted, hated her adoptive mother because she was fat, and fantasized about her real mother. She became obsessed with becoming pregnant after a molar (growth of tissue, not fetus) pregnancy. She decided she was going to be a mother, the best mother a baby could have, even though she was only nineteen years old, and didn't give herself much of a chance to get pregnant for real. What she wanted, she wanted NOW, even if she had to lie to everyone and murder an innocent woman. Was Darci crazy, or a cold-blooded psychopath? One psychiatrist claimed that Darci had different "parts" of her personality (but not Multiple Personality Disorder) which excused her from any culpability for her crime. Unfortunately, the doctor simply made herself sound like a loon on the stand in the courtroom. What it boils down to, is Darci took what she wanted, got caught, and showed no remorse for her crime, or empathy for the woman she killed.