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.
The story of Hollie Gazzard and Asher Maslin, who fell in love after meeting in a bar. However, Maslin was hiding his mental illness and when she ended the relationship, he decided no one else could have her.
The murder of Philip Croydon, who was found dead in a hotel room blindfolded with his hands tied. It was thought he had been the victim of a doomed sex game - but it transpired his wife Carol was hiding a dark secret.
How a once loving relationship turned sour when Kevin Nunn became increasingly controlling over girlfriend Dawn Walker. Jealousy and stalking ensued leading to a brutal murder.
How financial problems pushed Stephen Barnsdale Quean's 10-year marriage to the limit, leading him to strangle wife Chantelle to death. At first, he claimed she had attacked him.
The case of Portuguese national Hugo Quintas, who was instantly drawn to Hayley Richards. They had a passionate love affair, but when she fell pregnant, his jealousy led to murder.