Julia and Lydia Esdaile live with their widowed father, Willis, at Knockfane, a 'Big House' and farm where generations of the Esdaile family have lived for centuries. Willis Esdaile, obliged to preserve Knockfane for succeeding generations, and acutely conscious of the weight of his inheritance, inexplicably banishes his only son and heir, Edward, to live with the child's maternal grandfather. A series of unforeseen events threatens to sweep Knockfane from the family, and it falls to Julia and Lydia to carry on the Knockfane legacy.

This story of an Irish family is also the story of two sisters: bossy, confident, independent Julia, and gentle, caring, reflective Lydia, the younger sister and her father's favorite. Knockfane is an enthralling drama exploring inheritance, heirship and family legacy, set against the backdrop of the Ireland of its time and the conventions, customs, mistrust and suspicions which governed both Protestants and Catholics, as they come to terms with each other's world in a rapidly changing society.