A Scottish single mom (Emily Mortimer) has been writing letters to her deaf son (Jack McElhone), pretending they’re from his father, who’s away at sea; now the “father’s” ship has docked right there in Glasgow, and she has to hire a stranger (Gerard Butler) to pose as the seafaring dad. One shudders at what Andrea Gibb’s script might have become in the hands of hacks—some raucous farce, perhaps, or a cloying tearjerker. Instead, Gibb and director Shona Auerbach give it the kind of effortless insight and kitchen-sink realism for which the term “slice of life” originally was coined. The film is full of discoveries and low-key surprises, and Auerbach coaxes subtle performances from everyone; these characters aren’t accustomed to expressing themselves in words, so it’s all in their eyes and body language. J.L.