First-time director Bryan Bertino's no-frills thriller is a throwback to the 1970s' heyday of nasty, relentless movies in which ordinary, unsuspecting folks are trapped and terrorized by remorseless sociopaths, right down to the solemn assurance that it's based on a true story. There's nothing more to it than meets the eye, but Bertino understands the mechanics of suspense and knows how to use them. James (Scott Speedman) had everything planned: After proposing to his girlfriend, Kristen (Liv Tyler), at a friend's wedding reception, he'd surprise her with champagne, candles, rose petals -- the works – back at his family's isolated summer house. But Kristen said no – she's not ready for commitment – and now it's 4AM, she's in tears, he's humiliated, the trappings of fairy tale romance are just plain depressing and the night is about to get worse. Someone starts hammering on the door; it's a girl, asking if Tamara is home. Wrong house, James says, and she melts into the darkness. Odd. Even unsettling, if you stop to wonder how the light bulb over the door come unscrewed. James goes out to get Kristen cigarettes, and while he's gone, things get seriously scary: The girl returns, still asking for Tamara; a man in a crudely-fashioned mask appears at the window, Kristen's cell phone vanishes and the landline is dead. She's is a wreck by the time James returns, and his mechanically comforting words sound awfully hollow when someone takes an ax to the front door and James discovers that his tires have been slashed. Who are the strangers, and what do they want? Bleak and claustrophobic Bertino's film resembles the recent THEM/ILS (2006) and VACANCY (2007), because they're all rooted in the same murky pool of primal fears: That conscienceless killers lurk in every shadow, that no home is safe, that in an instant you can be cut off from help and forced, panicked and on the defensive, to fight for your life. Bertino isn't out to do more than push those buttons, but he hits every one and does it without making James and Kristen act like morons.