May 1991: In the seaside town of Castlerock in Northern Ireland and the bodies of two people - police officer Trevor Buchanan and nurse Lesley Howell - are found in a car filled with carbon monoxide. Their spouses were having an affair and apparently the pair are so distraught they have taken their own lives. Their adulterous spouses - Sunday school teacher Hazel Buchanan and dentist Colin Howell - had met in the local Baptist Church. Following the apparent double-suicide, they continued their affair secretly for some time but both later remarried. A series of disasters in Howell's life - the death of his eldest son, substantial losses in an investment scam, and the revelation that he had been sexually assaulting sedated female patients - led to him declaring that he was a fraud, a godless man and telling the elders of his church that he and Hazel Stewart had conspired together to murder their spouses nearly two decades earlier. That confession led to two of the most sensational murder trials ever seen in the United Kingdom, Howell's conviction for murder in December 2010 and Stewart's in March 2011, despite her protestations of innocence. Distinguished journalist Deric Henderson has been all over this story since it broke. Now, for "Let This Be Our Secret" , he has carried out extensive interviews with close relatives, friends and associates of Colin and Lesley Howell and Trevor Buchanan and Hazel Stewart. He has examined the 1991 police investigation that failed to detect a crime. And he has also explored how the affair embarrassed and then scandalised the Baptist Church. In "Let This Be Our Secret", Henderson has produced the definitive account of one of the most extraordinary murder cases to hit these islands for decades.