Harold Henthorn calls 911 to report that his wife Toni has been gravely injured after falling off of a cliff on a remote trail. National Park Service Special Agent Beth Shott uncovers suspicious details and inconsistencies in Harold’s story.

As Special Agent Shott investigates the suspicious death of Harold’s wife Toni, anonymous letters and phone calls lead authorities to reopen an investigation into the death of Harold’s first wife 17 years earlier.

As the investigation into the suspicious death of Toni continues, Special Agent Shott learns something startling about Harold’s unusual relationship with his sister-in-law. Shott is joined by FBI agent Jonny Grusing who specializes in serial killers.

A search of the Henthorn home leads investigators to expose one of Harold’s biggest secrets. Shott and Grusing, her FBI partner, are confident that Harold murdered Toni, but they must assemble an airtight case with every scrap of evidence they can find.

Yosemite: a hand is found, a serial killer confesses. But he’s lied about committing hundreds of murders. Is this one real – or a false confession?

Don and Kim zero in on serial killer Henry Lee Lucas. They find evidence in Summit Meadow that seems to match his story -- but is Lucas lying?

Hikers find a skull. Years later, Kim Tucker’s son Cullen takes on the case. After 40 years, Jane Doe is identified with new DNA technology.

We meet Jane Doe’s friends, learn about her family, life in a cult and other men who may have killed her. Investigators name their likely perpetrator.