Based on the life of a Victorian serial killer, Mary Ann Cotton poisons three of her husbands and eleven of her children before she is caught and hanged for the murders.

Based on a true story of the devout Catholic British Lord Frank Aungier Pakenham, 7th Earl of Longford, and his controversial, colorful, headline-making friendship with one of Britain's most notorious criminals, child murderess Myra Hindley.