24-year-old Meredith Emerson disappears New Year's Day on a hike up Blood Mountain. Eyewitness accounts of a strange toothless man with a dog lead investigators to Meredith's remains, and uncover several unsolved murders.

239 passengers vanish in March of 2014, never to be seen again. Shortly after takeoff, a routine flight becomes a trip from hell when pilots stop responding and the plane disappears from radar.

A Catholic priest was found with his throat slit in his church of 32 years. Did Father Kunz's investigation of sex abuse in the church play a role in his unsolved murder?

10-year-old Lindsey Baum disappeared while walking home alone in a small town in Washington state. Her remains were discovered eight years later, more than 100 miles away.

2-year-old Arianna Fitts vanishes from San Francisco after her young mom is discovered murdered and buried in a local park. Just days earlier, the mom was on her way to go meet her daughter's babysitter.

A young police officer is ambushed and shot with a 12-gauge shotgun in the middle of the night on his way home from work, but this isn't the only unsolved mystery in the small and quaint community of Bardstown, Kentucky.