Season 1
- 1Episode 129 Apr 2016
- 2Episode 26 May 2016
- 3Episode 313 May 2016
- 4Episode 420 May 2016
Set in Northern Ireland, The Secret is the story of a real-life double murder. James Nesbitt plays Colin Howell, a respectable dentist and pillar of the community, who became a killer in partnership with a Sunday school teacher, Hazel Buchanan, played by Genevieve O'Reilly.