Released in theaters on September 25, 2009, a little movie titled Paranormal Activity quickly became one of the most successful horror phenomenons in modern cinematic history. Now, on the occasion of the film's 10th anniversary, we speak with lead actress Katie Featherston about the initial audition that would ultimately change the course of her life, the unusual process of filming an improvised movie, and the runaway success of the film and its subsequent sequels. Following our conversation with Katie, you'll hear a replay of our 2009 interview with writer/director Oren Peli, which was conducted during the week of the film's initial release.