Charlie Cullen was an experienced registered nurse, trusted and beloved by his colleagues at Somerset Medical Center in New Jersey. He is also one of history’s most prolific serial killers, with a body count potentially numbering in the hundreds across multiple medical facilities in the Northeast.

This 7-part season is filled with expert interviews and in-depth portraits of some of America's most infamous killers including John Wayne Gacy, David Berkowitz, Richard Ramirez, James DeAngelo, Aileen Wuornos, Jeffrey Dahmer, Andrew Cunanan, Ted Bundy and many others.