
World's Most Evil Killers delves straight into the stories of the world's most prolific killers. Each episode focuses on one notorious killer and features first-hand accounts of their behavior; such killers range from Fred and Rose West, Ed Gein, the Clown Killer, to the Milwaukee Cannibal. Accounts are also given by detectives who ran the cases, journalists who reported on them, relatives, experts on analysis, and sometimes even survivors.

Lonnie David Franklin Jr. is better known by the nickname Grim Sleeper; he lures vulnerable women into his car before murdering and sexually assaulting them for more than two decades.

A profile into the murderer who terrorized the gay community as the "Trash Bag Killer" and confessed to killing 32 victims.

The story of the Beltway sniper attacks; John Allen and his teenage accomplice carry out a brutal series of shootings that kill ten people.

One of the most prolific serial killers in Canadian history is dubbed "The Pig Farmer Killer" by the media.