A prankish comedy-thriller overtly about desperation and insecurity, Baghead begins with a dead-on Q&A at a Los Angeles indie film festival, where an underground auteur (Jett Garner) condescendingly responds on matters of budget and improvisation. (“Do you plan every word you’re going to say every day?”) A quartet of unemployed actors, after being ejected from the fest’s afterparty, ruminate about their careers and decide to hole up in a house in the sticks to write a screenplay for their own calling-card vehicle. This second feature by the Duplass brothers, with co-writer/lead actor Jay from The Puffy Chair now sharing directing credit with Mark, soon becomes a kind of mumblecorish spin on The Blair Witch Project (or a riff on that movie’s founding marketing myth that it was authentic found footage). But the crux of the suspense is where the joking will stop, both among the deceptive and game-playing characters and by the filmmakers. As a hybrid, it’s destined to disappoint horror fiends who take its predator-in-the-woods moves at face value, but it delivers on its premise that the shameless scheming of a friend can be a scarier phenomenon than a boogeyman with a knife.