tells the incredible true story of Britain's deadliest terrorist atrocity and the most fatal terrorist attack on America before 9/11: the bombing of Pan Am flight 103, when 270 people lost their lives on the night of December 21 1988.  The documentary will speak to individuals closely linked to the disaster and the years-long investigation that followed it.  With access to victims' families, investigators, intelligence officers and other key figures who have not spoken until now, the series will examine unanswered questions and explore the truth behind the atrocity to provide a definitive account of the bombing and its aftermath and - ultimately - who was responsible.