Amy Adams and Matthew Goode have the charm necessary to float a romantic comedy like "Leap Year," and this is a story that needs their buoyancy. A sort of conspiracy forms between the audience and the screen: We know what has to happen, and the movie knows what has to happen, and the point is to keep us amused. "Leap Year" does better than that: It made me care. It does that by not being too obvious about what it is obviously trying to do.