Unease, in the sense of Woody Allen-style comic neurosis, is one of the hallmarks of the so-called "mumblecore" movement, indie films made on a shoestring with hefty amounts of improvisation and semi-romantic, semi-cynical, semi-hopeful story lines. "Baghead" marries that kind of emotional distress to the spiky thrills of horror films. Amazingly, it works. It's nail-biting fun.

After seeing a cocky colleague's mediocre film win over a film festival audience, four underemployed actors decide that creating their own project is a likelier path to success than waiting for casting agents to notice them. They head off for a weekend in a remote cabin to brainstorm ideas, and as the refreshments flow, they settle on an uninspired romantic comedy that reflects their own unresolved relationships.

Balding, pudgy Chad (Steve Zissis) and his attractive friend, Matt (Ross Partridge, who looks like a rough sketch of Mel Gibson), are in an unacknowledged competition for sexy ingénue Michelle (Greta Gerwig). Meanwhile fading never-has-been starlet Catherine (Elise Muller) wants Matt to commit after 11 on-again, off-again years.

Their interactions are cleverly sketched as they alternately flirt, sulk and back stab, their insecurities sabotaging the writing process. When Michelle reports glimpsing a menacing figure with a grocery bag over his head lurking in the woods, however, inspiration strikes. Why not make a slasher movie? The other three dismiss Michelle's encounter as a side effect of boozing until they encounter a fifth wheel wearing a paper sack. The film takes a "Blair Witch" turn as the actors freak out at their predicament, with sexual jealousies undermining their solidarity.

The plot is just tricky enough. "Baghead" sports some clever film-within-a-film switchbacks but never goes overboard into self-conscious genre parody. There are real scares and genuinely touching moments, and they don't short-circuit each other. Writer-director brothers Jay and Mark Duplass keep us off base about what to expect, and what kind of a film it is that we are watching. Is it a relationship movie with horror elements or vice versa?

The actors, whose careers are not that much different from the sideliners they play, make their characters so rounded that you're likely to forgive their character flaws. No one indulges in the death-justifying excesses of "Friday the 13th" victims -- there's no sex, no drug abuse -- and you don't want them to be terrorized just because they're passive-aggressive wannabes. Chad's angriest moment comes when his jealousy boils over and he accuses Matt of having "Elvis hair, man!"

When the origami model of the plot finally unfolds, and the well-justified surprises are disclosed, there are still a couple of revelations up the Duplass brothers' sleeves. Foremost among them is that it's possible to make a scary yet sweet movie about recognizable human behavior.

Colin Covert • 612-673-7186