Season 1, Episode 1 My Identity Adopted as an infant, Gary L. Stewart always struggled with his identity. After 39 years, the lifelong search for his biological parents reveals a truth he never could have imagined. Season 1, Episode 2 The Search After learning that his father may have been the Zodiac Killer, Gary brings The New York Times best-selling true crime author Susan Mustafa into the fold to help uncover more information about him. Over the next two years, they follow a dark trail filled with unexpected discoveries as Gary attempts to find some closure. Season 1, Episode 3 The Discovery Gary's story takes a turn when he realizes his book could be a betrayal of his newfound relationship with his biological mother. When Gary goes up against a community of Zodiac fanatics with ulterior motives, he reveals new information that has never been shared. Season 1, Episode 4 The Truth Armed with DNA evidence that links his father to the Zodiac Killer, Gary forges ahead trying to uncover his truth. Meanwhile, a San Francisco-based private investigator digs into Susan and Gary's claims. The questions that have haunted Gary for decades culminate in an unexpected end.

“Part of the reason why the Zodiac case was not solved was due to a lead detective’s obsession,” Davidson said. “I can’t reveal too much more because, actually, there’s an element in the Zodiac case that’s really not been talked about before that we uncovered and got people to talk about how that explains why it wasn’t solved in the 1970s.” Davidson went went on to say that there existed a “culture within the (San Francisco) police department that you don’t talk, you don’t rat out your fellow officers. I wouldn’t go as far to say that there was a cover up, per se, but there is certainly information that these former detectives were not talking about that I ultimately did get them to talk about.”

Donnie Wahlberg will host Very Scary People, a six-episode HLN series that chronicles the lives of the most frightening individuals in recent history. Each two-hour episode traces their criminal acts. John Wayne Gacy starts things off March 17, Charles Manson goes March 24, and the NorCal Rapist, Aileen Wuornos, Zodiac Killer and Rev. Jim Jones follow.