In 1930s Yorkshire, a spirited new headmistress brings inspiration and modern ideas to an all girls' school and shakes up the more conservative-minded residents of South Riding.

Set in the 1930s, Britain is in depression and still scarred by the effects of World War I. Young and passionate Sarah Burton (Anna Maxwell Martin) returns to her conservative home county, bursting with modern ideas. As the new headmistress in South Riding, she inspires her girls, including Lydia Holly (Charlie May-Clark), a scholarship student from the slums, to think for themselves. But not everyone sees eye-to-eye with Miss Burton. She finds a few allies, Joe Astell (Douglas Henshall) being one; but the sparks really start to fly when she crosses paths with Robert Carne (David Morrissey), a haughty landlord whom she despises.—L. Hamre