For more than 25 years, "Dateline" has brought viewers investigations into some of biggest mysteries in America. This entry in the franchise takes a second look at some of the most mysterious cases of recent history. Hosted by Emmy-winning journalist Craig Melvin, the show explores the stories through firsthand accounts told by people who are close to the crime, including investigators who dedicated their time to the cases and family members who are still trying to confront the tragedies that befell their loved ones.