Poppy (Sally Hawkins) is an irrepressibly free-spirited school teacher who brings an infectious laugh and an unsinkable sense of optimism to every situation she encounters, offering us a touching, truthful and deeply life-affirming exploration of one of the most mysterious and often the most elusive of all human qualities: happiness. Poppy?s ability to maintain her perspective is tested as the story begins and her commuter bike is stolen. However, she enthusiastically signs up for driving lessons with Scott (Eddie Marsan), who turns out to be her nemesis -- a fuming, uptight cynic. As the tension of their weekly lessons builds, Poppy encounters even more challenges to her positive state of mind: a fiery flamenco instructor, her bitter pregnant sister, a troubled homeless man and a young bully in her class, not to mention that she has also thrown out her back. How this affects not only Poppy's world view but also the outlook of those around her begs the question -- glass half full or half empty?