World's Most Evil Killers delves into the gripping real-life stories of the world's most terrifying and prolific killers. From Fred and Rose West to Ed Gein – The Clown Killer – and even to The Milwaukee Cannibal. Each episode focuses on one notorious killer and features authentic first-hand accounts of their behavior, from detectives who ran the case, journalists who reported on the stories, relatives, and at times survivors, alongside series experts who provide analysis.