With this third feature, Aaron Katz (Dance Party USA, Quiet City) tries to extend the much-hyped “mumblecore” indie past its usual postcollegiate solipsism by marrying it to the detective thriller. The result is pretty entertaining, though most of that entertainment derives from Katz’s skillful exploitation of gumshoe formula, which ultimately just confirms one’s suspicion that mumblecore is a generational phenomenon but an artistic dead end. The hero (Cris Lankenau) is a slacker in Portland, Oregon, who’s earned a degree in forensic science but prefers to spend his time slumming at an ice-packing plant; when his ex-girlfriend inexplicably disappears, he and an intrepid coworker (Raul Castillo) make like Sherlock Holmes and Dr. Watson. Of course, allowing this to become a mere genre piece wouldn’t be cool, so ultimately Katz lets the mystery degenerate into a shaggy dog story and ends with the young sleuth and his sister aimlessly rapping in a parked car.