The cases include the abduction and murder of 10-year-old Bernadette Connolly in Co. Sligo in 1970. Bernadette vanished while cycling her bike; her body was found at a bog four months later. Also profiled in Unsolved is the fatal shooting of Chief Prison Officer Brian Stack the only murder of a prison officer in the history of the state. Another case examined is the double killing of Eddie McCabe and Catherine Brennan in Tallaght in 1995. Gardai believe Eddie McCabe was the intended target of the attack and Catherine was shot in the head simply because she was a witness to the killing.

Unsolved also looks at the murder of Galway taxi driver Eileen Costello O'Shaughnessy, and the murder of Marie Kilmartin whose body was found hidden in a bog drain in Co. Offaly in June 1994. This book also charts the investigation into the tragic disappearance of two men in Cork and the murder of a third man in the city eight months later.

The murder of 15-year-old Tyrone schoolgirl Arlene Arkinson is also examined in detail. Arlene disappeared after a night out in August 1994. Despite extensive searches in both Donegal and Tyrone, Arlene's body has not yet been found.

Through in-depth interviews with a number of families of murder victims, Unsolved illustrates that their grief is compounded by the failure to catch those responsible: evil, violent people, still living among us.