One should know as little as possible in advance about the plot of cinematographer Shona Auerbach's subtle and graceful directorial debut, written by Andrea Gibb. So let's just say that the main characters are a single mother (Emily Mortimer), her deaf nine-year-old son (Jack McElhone), his mysteriously absent father, a sailor hired by the mother to briefly impersonate the man, and the Scottish port setting. Considering this film and David MacKenzie's Young Adam, an exciting new Scottish cinema may be taking shape. PG-13, 102 min. Century 12 and CineArts 6, Landmark's Century Centre.