IN Newcastle-on-Tyne in 1968, an 11-year-old girl named Mary Bell took the lives of two small boys within weeks of each other. She was subsequently tried and convicted for manslaughter, and detained for 12 years. In Cries Unheard, Gitta Sereny explores the social context of the case, based on interviews she held in secrecy with Mary Bell over a period of several months. Bell was to receive part of Sereny's advance. Since Bell's release in 1980, she had managed to elude being discovered by the press. Early last year, once news broke of the book's contents, she was tracked down ten days later - to the home she shared with a 13-year-old daughter who had no idea of her mother's past. In the new introduction to the paperback, Sereny records candidly that ensuing media frenzy and its consequences, and how both she and Bell responded to it.