With the Saw and Hostel franchises, horror films had said it all about torture porn. Now it was back to basics: “found footage” of a couple scared witless in a haunted house. Shot by writer-director Oren Peli in his home in a week for $15,000, Paranormal Activity earned nearly $200 million at the worldwide box office and cued its own popular annual series. But the movie’s real achievement is subtly cinematic: evoking screams with the opening of a door, the shadow on a wall, the sight of a woman standing mute and motionless for hours over her sleeping beau. Whether or not Satan is behind it all, this is an indelible, truly haunting image of domestic disturbance.