The case involving the murder of Rachel O'Reilly examines how her coffin was exhumed, and the cryptic letter her husband Joe had written to her. There was another breakthrough when groundbreaking technological evidence threw Joe's alibi into doubt. After more than two years of painstaking detective work, they finally had enough to charge him.

The opening episode looks closely at the start of the investigation and how, as it progressed, Rachel's husband Joe become the focus of the police's investigation.