Denis Donaldson answered to former Sinn Féin leader, Gerry Adams, and was at the heart of the republican movement for 20 years. So, how did he manage to spy for so long for the British? The Bel Tel finds out. 

Host: Ciarán Dunbar. Guest: Belfast Telegraph Political Editor, Suzanne Breen.

The BelTel brings you some of Northern Ireland's top journalists, Allison Morris, Sam McBride and Suzanne Breen to name but a few, giving you the inside stories behind what is in the news. Presented by Ciarán Dunbar, the Bel Tel investigates, debates and informs every Monday, Wednesday and Friday.

Advertisement