Bestselling author Henry Hemming discusses Four Shots In The Night, an investigation into the ruthless murder of Frank Hegarty, a British agent who infiltrated the IRA at the height of the Troubles.  Hegarty worked closely with Martin McGuiness and his information was highly valuable.  His death from four shots to the head in May 1986 – possibly fired by another British agent – prompted one of the biggest murder investigations in recent British history.  Henry analyses the network of secrets, lies and betrayals of both the IRA and British intelligence and asks how far any spy should be allowed to go in the pursuit of intelligence.