Britain's Deadliest Lovers season 1 episode 1
Episode title: The 18 Year Secret (Colin Howell and Hazel Buchanan)
The crimes of Co Derry dentist Colin Howell, who in 2009 admitted gassing to death his first wife Lesley, as well as Trevor Buchanan, the policeman husband of his then-mistress Hazel 18 years earlier.
