When it comes to serial killers, there aren't many stories more chilling than the one of Fred and Rosemary West. The murderous duo raped, tortured and murdered at least a dozen young British girls between 1967 and 1987 in Gloucestershire, including several of their own daughters. Learn of how two of Britain's most notorious serial killers were able to get away with their crimes for so long, how they hid the victim's remains within the confines of their own home, and how they were eventually taken down.