England, 1873. Clara Blackstone has just been released after one year in a private asylum for the insane. Clara has two goals: to reunite with her husband, Henry, and to never–ever–return to the asylum. As she enters Durham, Clara finds her carriage surrounded by a mob gathered to witness the imprisonment of Mary Ann Cotton–England’s first female serial killer–accused of poisoning nearly twenty people, including her husbands and children.
Clara soon finds the oppressive confinement of her marriage no less terrifying than the white-tiled walls of Hoxton. And as she grows increasingly suspicious of Henry’s intentions, her fascination with Cotton grows. Soon, Cotton is not just a notorious figure from the headlines, but an unlikely confidante, mentor–and perhaps accomplice–in Clara’s struggle to protect her money, her freedom and her life.