"It was like the floor fell out from underneath me." Mariska Hargitay's new documentary exposes one of her family's biggest secrets. The daughter of blonde bombshell Jayne Mansfield makes her feature directorial debut with the HBO film,

Jayne Mansfield was an actress and a sex symbol of the 1950s and early 1960s, and now her famous daughter, Mariska Hargitay, wants to understand her better.

The documentary, which marks Hargitay's feature film directorial debut, will premiere on HBO and Max on June 27