On the 27th of April 2008 the horrific case of Josef Fritzl sent shockwaves around the world, news report after news report gave details of a quite unbelievable story. For 24 years Josef Fritzl had kept his own daughter captive in a cellar beneath his house, in that time he had used her as his very own sex slave, fathering seven children. This film sets about uncovering exactly why Josef Fritzl carried out his terrible crimes and how he managed to keep them a secret for so long