Addy and Prue Fairweather live with Nell, their widowed mother, in a flat above her shop on the Scotland Road. The sisters, however, are very different. Addy is dark-haired, plain and always in trouble whereas Prue is flaxen-haired, blue-eyed and as angelic as her looks imply. To make matters worse, Nell makes no secret of her preference for the younger girl, increasing Addy's jealousy and resentment.