Maria (Saoirse Ronan), a primary school teacher doing her best to inspire a class of 10-year-olds, is stifled by one unruly and chaotic student. With her career in question and the child's behaviour spiralling, she makes a series of bad decisions that lead to her accidentally taking and locking this 'bad apple' in her home. Maria tries desperately to backtrack, but when the class starts flourishing and the staff and parents are thrilled with the improvement, she finds herself in a very complicated predicament.
