At Christmas 2008, Foreign Office employee Annabel Tilson's body was found in a frozen lake, the assumption being that she killed herself after suffering a miscarriage and demotion at work when her lap-top, containing sensitive information, was stolen. Now her twin Minnie has unearthed a video showing that Annabel met somebody prior to her death and was probably murdered. Sandra learns that Annabel was deliberately made a scapegoat to get her out of the way on discovering her married boss's affair with a colleague. She also stumbled on insider information trading, but the key to her death turns out to be her personal, rather than professional life.