The murders happened shortly after 8 o'clock on the morning of 25th June, 1988. Media speculation was rife on the so-called 'Pangbourne Massacre', but no-one knew why 32 adult residents of an exclusive housing development had been brutally slain and their children abducted.

In the face of the total bafflement and continuing public outrage, the police called in Dr Richard Greville, the MET's Deputy Psychiatric Adviser. But as Greville sifts the evidence and decides to follow new lines of enquiry he is drawn to a conclusion as appalling as the crime itself...