A mother (Susanne Wuest) builds an emotional wall between herself and her nine-year-old twin sons (Lukas and Elias Schwarz) in the Austrian horror import, Goodnight Mommy. To add to the viewer's discomfort, bandages from a recent surgery cover Mom's head. Mommy looks like a mummy. That's the set-up for directors Severin Fialo and Veronica Franz's debut, a movie that's tightly crafted, nearly to the point of suffocation. Set in a modern, sparsely decorated home in the Austrian forest, the movie serves up off-kilter behavior that remains eerily ambiguous. An example: Mom won't feed one of the twins. The boys insist that Mom's personality has changed; she's no longer the loving parent they knew. Eventually, Mom removes the bandages, and the boys become increasingly convinced that she's an impostor. Insular and creepy, Goodnight Mommy thrives on atmospherics and restraint. Fialo and Franz also do a good job of making us feel uncertain about where to place our sympathies. There's no denying the movie's directorial competence, careful cinematography and chilly production design, but Goodnight Mommy eventually turns into an extended torture fest that revolves around a twist that didn't really take me by surprise. In sum: This one's better in its build-up than in its resolution. Fortunately for horror fans, the build-up occupies most of the movie's 99 minute running time.