After he criticises police procedure in the aftermath of a murderer's capture, DS Sean Stone's superiors want him out of the way, so they assign him to a new 'unit' at the MPB with analyst Ruth Hattersley. However, the case of a vanished 16-year-old girl soon has the unorthodox detective back out in the field with his new partner. Looking into a spate of teen suicides, he believes he has discovered a killer preying on vulnerable youngsters.