The story of two journalists who investigated an unsolved mass murder in Northern Ireland.

No-one has ever been charged or convicted.

Episode 8 – Who Watches the Watchmen

As the dust settles on a historic judgement by the Investigatory Powers Tribunal – Barry and Trevor say their fight is not yet over, demanding a full public inquiry to reveal the full extent of surveillance.

Can a wide-ranging review of surveillance powers commissioned by the Chief Constable of the PSNI provide answers - and can a balance between national security legislation and the need for transparency ever truly be achieved?

A BBC Northern Ireland Production