Poppy is the kind of irrepressibly chipper person who attempts to start conversations with random strangers; when they act standoffish, she says things like, "I won't bite!" When her bicycle is stolen, she merely laments she didn't have a chance to say good-bye to it. In short, she's the kind of person who is so goddamn cheerful you'd like to smack her in the face.

But something happens over the course of Happy-Go-Lucky: Poppy wins you over. Poppy's happiness is something of a mystery; both her sisters are miserable, and her flatmate is snide and sarcastic. But Sally Hawkins' remarkable performance doesn't hit one false note. British director Mike Leigh (Vera Drake, Secrets & Lies) improvises extensively with his actors before writing a script, and the film, as with all his work, feels spontaneous and true.

Poppy's an elementary school teacher who acts the same age as her students, but when one kid starts beating up the others, she handles it maturely. She's truly tested, though, by her driving instructor (Eddie Marsan), a wretched, miserable piss-ant whose bitter nature is at complete odds with Poppy's. His spittle-flecked fury and frustration at the world is so misguided and unnecessary, it makes you wonder if perhaps Poppy's really onto something with this whole happiness thing.