Lilies details the lives of Iris, May and Ruby Moss, three Catholic sisters living with their widowed father and brother in a terraced house in Liverpool in the early 1920s. The story is set in the years immediately after First World War and, as such, the after effects of that conflict are apparent. The story depicts a life lived on a knife-edge of poverty, tempered by various kinds of love. All three girls must make their own way in the world. In the course of the series, each sister tastes passion for the first time, and their lives, newly launched, are changed forever.