Josef Fritzl was a 73-year-old retired engineer in Austria. He seemed to be living a normal life with his wife, Rosemarie, and their family,although one daughter, Elisabeth, had decades earlier been lost to a religious cult. Throughout the years, three of Elisabeth's children mysteriously appeared on the Fritzls' doorstep; Josef and Rosemarie raised them as their own. But only Josef knew the truth about Elisabeth's disappearance...

For twenty-four years, Josef had imprisoned and molested Elisabeth in his man-made basement dungeon, complete with sound-proof paneling and code-protected electric locks. There, she would eventually give birth to a total of seven of Josef's children. One died in infancy and the other three were raised alongside Elisabeth, never to see the light of day.