Four girls have disappeared in North London. Three are already dead. Britain's most prolific child killer Louis Kinsella has been locked up in Northwood high-security hospital for over a decade. Now more innocents are being slaughtered and they all have a connection to his earlier crimes. Psychologist Alice Quentin will do anything to help save a child - even if it means forming a relationship with a charismatic ruthless murderer. But Kinsella is slow to give away his secrets and time is running out...