Having tracked down her mother's murderer and helped to track down the man who abducted and murdered couples from all over the country, Catherine Colson-Sayers has got the bug for investigating and sets up her own Private Investigations Agency.In this story Catherine has to work out who is bumping off patients at a local hospital. Doctors and Nurses become the usual suspects, but Catherine, and her business partner, Emma, dig deeper and harder to find out more.