Greta Gerwig has been called the "It Girl" of the mumblecore genre, and it's easy to see why. In "Baghead" -- which epitomizes such ultra-low-budget conventions as naturalistic settings, freewheeling (some might say nauseating) camera movements, improvised-sounding dialogue and spontaneous, often observantly funny performances -- Gerwig shines with her own loopy brightness.

Gerwig plays Michelle, an aspiring actress who, with three other wannabes, travels to a remote cottage on California's Big Bear Lake to write a film. She is there as a nominal date for Chad (Steve Zissis) but soon sets her sights on handsome actor and guerrilla auteur Matt (Ross Partridge), who has brought his on-and-off girlfriend, Catherine (Elise Muller).

Written and directed by Jay and Mark Duplass ("The Puffy Chair"), "Baghead" is at its best when it captures the subtleties of romantic machinations, macho power plays and the indignity of women aging in Hollywood. But with the arrival of the titular character, who may or may not be terrorizing the group with scary nighttime appearances, the movie devolves into territory already well trod by "The Blair Witch Project." Still, "Baghead" provides a diverting showcase for actors you may never have heard of but who deserve a shot at fame and fortune.

By Ann Hornaday / The Washington Post

Baghead

Rating: 2 and a half stars (out of four)

Cast: Ross Partridge, Steve Zissis, Jett Garner.

Running time: 80 minutes.

Rated: R; profanity, sexual content and nudity.