Rhoda Brook is a lonely peasant who works long hours as a milkmaid to support her and her young son. A prior affair with Mr Lodge, a wealthy employer – by which her child was conceived – lead her to exclusion from the rest of the town’s inhabitancy and lead Rhoda to the decision of living away from the village’s glare on the outskirts of town. Though both her and her son are ignored by Mr Lodge, Rhoda keeps a watchful eye on his business, especially after she hears of his marriage to a much younger woman.

Gertrude, the pretty 19-year-old bride, unwittingly fans the flames of a long-term rage inside Rhoda. Stricken with jealousy, her subconscious thoughts surface in her sleep as she innocently dreams of grabbing the girls’ arm in a defensive tackle, only to find that her dreamed actions were not so innocent, as Gertrude meets her for the first time the next day and reveals to her a mysterious mark on her arm.

Rhoda tries to replace any thoughts of witchcraft as sheer coincidence, but the marks on Gertrude’s arm rapidly worsen, and she resorts to visiting a type of witch doctor named Conjuror Trendle to find the cause; much to Rhoda’s dismay, as she is asked to lead the way to the home of the exorcist and fears the loss of a good friendship should the identity of the culprit be revealed. Surely enough, Gertrude was shown the face of her “attacker”, though a cure for her illness had yet to be found.

The villagers began to suspect Rhoda of witchery, and she and her son became progressively distant from the town, eventually disappearing for good. Over the next 6 years, Gertrude’s arm had continued to wither, and the fact that she had brought no children to her husband made her worry that Mr Lodge would reject her. Having tried every natural remedy and witch spell alike, she made a last attempt at a cure by first travelling back to the home of Conjuror Trendle.

She was given an option – most likely the last – in which she could touch her arm with the neck of a recently hanged man. In doing so, her blood would supposedly “change” and her arm would be healed. Seizing the next opportunity, Gertrude set out for Casterbridge – a town of which a man would be hung for arson – while her unknowing husband was away on business. The executioner – persuaded by the sight of a mysterious and attractive young woman – agreed to let her stand by while the execution took place and touch the neck of the convict as soon as he had been hung.

No sooner had she rested her withered arm upon the neck of the young man on the day of the hanging that she realised Rhoda Brook and her husband were standing close behind; that he had lied to her about going away on business in order to secretly witness the execution of, as she had come to realise, his and Rhoda’s son. Just as Rhoda – filled with grief and rage – pulled her away from the corpse, Gertrude collapsed of shock, ultimately dying before ever making the journey back home.

Following the funeral of his young wife, Mr Lodge retired and moved away to the other side of the county, having had his property transformed into a reformatory for boys and donating the proceeds to Rhoda. She, however, refused to have anything to do with it and resumed her work as a milkmaid. This would occupy her until she was a lonely old woman with tattered grey hair and a bent posture; stirring intrigue and curiosity as other workers around her could only imagine, with all she had been through in her life, what thoughts were going through her mind.