Thanks largely to some of the best vocal performances in recent memory, this scrappy little flight of fancy is wildly unexpected in its offhand, unpretentious manner. At least until it becomes a bit too infatuated with its own offhand, unpretentious manner. Still, its ability to make something stirring out of almost literally nothing—I mean, the notion of building a feature film, even a ninety minute one, on the back of a seashell is the least high of all high concept pitches—is pretty astounding.