One third of the world's female prison population is in America; 30,000 of them are serving long sentences for murder. But unlike many male murderers, female killers tend to know their victims. So what pushes ordinary women to kill people they know and love? This documentary meets three women behind bars for murdering people they knew. Each has an extraordinary story. Amber Hilberling was 19 years old and seven months pregnant when she pushed her husband out of a 25-storey high-rise window. She has always maintained her innocence. Patricia Ignacio admits bludgeoning to death her cousin with a rock, and Ana Trujillo murdered her boyfriend by stabbing him 25 times with her stiletto shoe.