Penny Marshall investigates the dark secret of women who sexually abuse children.
Female sexual abuse of children goes against everything we want to believe about women.
The thought of mothers overstepping the boundaries of love to abuse their children is so threatening and shameful that it has become one of the most under-reported of crimes.
However, recent research suggests that they are responsible for up to 20 per cent of all abuse.
Because there was often denial that women could behave in such a way, it has remained under-researched and many incorrect assumptions and beliefs still surround the subject, even among professionals.
Penny hears shattering stories from the abused and talks to those working with offenders to try to understand their behaviour and motivations.