He is the serial killer you've never heard of … until now. In 1973, 22-year-old Doug Gretzler embarked on a cross-country road trip that spiraled into a brutal killing spree. In just three weeks, he and his accomplice, 28-year-old Willie Steelman, murdered 17 people. Their motive? A mystery that has left family members, law enforcement and experts baffled for decades. Drawing from first person interviews and over 500 hours of recorded conversations with Gretzler himself, hear his darkest confessions and the chilling psychology behind his crimes for the very first time.