In 1967, Connie and Carolyn Hevener are murdered at an ice cream shop. The crime seems like a botched robbery, but the killer remains at large four years later.

Donna Fowler's disappearance isn't her first, but it's her last. Years later, Stacy Belcher vanishes too. Two families face the horror of a long-time monster.

Marilyn Kananen, 65, disappears. Her children suspect their abusive father, gone for 15 years, has returned. Detectives find evidence that turns the case upside down.

The skull of 13-year-old Heather Church is found two years after her abduction. Her case leads investigators to one of the most prolific serial killers in U.S. history.

Marlene Major vanishes in 1980, presumed to have fled her abusive husband. Only one man knows her fate, and the truth is far darker than imagined.

Lisa Summers, 16, is found dead with little evidence. Nearly two decades later, cold case detectives use old witnesses and new technology to solve her murder.