The Wrong Mother

I've enjoyed The Wrong Mother by Sophie Hannah. It was published the year before as Point of No Return (why change the title?) and it was recently on ABC1 as a two part series called "Case Sensitive" (which was a bit different to the book). Geraldine Bretherick and her daughter Lucy are found dead in their home and it appears to be a murder suicide. Her husband Mark insists Geraldine was a loving mother and would not have done this crime. A young mother, Sally, sees Mark on the news and recognises that he is not the same Mark Bretherick whom she met at a conference a year earlier and with whom she had a brief affair. Sally anonymously passes this information to the police and then begins her own investigation, the consequences of which further complicates the police investigation. 4/5